Absorbent barrier structures having a high convective air flow rate and articles made therefrom

ABSTRACT

Absorbent articles with improved protection and comfort by use of an absorbent barrier structure. This is achieved by the selection of individual components meeting specific requirements such that the combination thereof provides the absorbent articles with desired performance.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 09/883,434, filed Jun. 18, 2001, which is acontinuation-in-part of and claims priority under 35 U.S.C. §119 to PCTApplication No. US 00/17084, filed Jun. 21, 2000.

FIELD OF INVENTION

[0002] The present invention relates to absorbent articles which providesuperior protection against wet through under impact or sustainedpressure, and high convective air flow therethrough for skin health andcomfort benefits. In particular, the present invention relates to anabsorbent barrier structure for such articles.

BACKGROUND OF THE INVENTION

[0003] Many known absorbent articles such as diapers, incontinencearticles, feminine hygiene products, and training pants, typicallycomprise absorbent core materials located between a liquid perviousbody-side liner or topsheet and a vapor permeable, liquid impermeableouter cover or backsheet. The bodyside liner allows bodily liquids toflow through easily and towards the absorbent core. The absorbent coretakes up the liquids quickly. Thus, no excessive pooling of liquidsoccurs on the body-facing surface of the absorbent article. The outercover is typically liquid impermeable such that there would be noleakage from the absorbent article. However, because the disposableabsorbent article may be worn for hours, sometimes after the absorbentarticle has taken up liquids, perspiration from the wearer's body, andliquid vapors escaped from the absorbent core, can get entrapped in thespace between the absorbent article and the wearer's skin, resulting inan increased relative humidity in the occluded area. As is known in theart, the increased relative humidity leads to discomfort andoverhydrated skin, which is prone to skin health problems, especiallyrashes and other contact dermatitis.

[0004] Generally, liquid impermeable backsheets are well suited toprevent the leakage of bodily fluids (such as urine, menses or fecalmatters) from the absorbent material to the outer garment of a wearer.However, the use of such an impermeable backsheet can result in a highdegree of humidity in the absorbent article when the absorbent articleis in use such that a relatively elevated skin hydration levels mayresult.

[0005] The problem of high relative humidity near the skin in anabsorbent article has been addressed in the art through a number ofmeans. For example, U.S. Pat. No. 5,137,525 uses mechanical means toincrease airflow in the article. Alternatively, breathable outer coverhaving microporous or monolithic films may be used in an absorbentarticle to allow air and water vapor diffusion. PCT Publications WO98/58609 discloses absorbent article using other water vaporpermeability, liquid impermeable barrier materials as the backsheet. PCTPublication WO 00/10497, WO 00/10498, WO 00/10499, WO 00/10500, WO00/10501 relate to breathable absorbent articles exhibiting the severalproperties of the dry and wet articles. The absorbent articles disclosedin these publications typically have high permeability zones within theabsorbent core, for, example, by aperturing the absorbent core or byvarying high absorbency material content in portions of the core.However, the absorbent articles include microporous backsheets throughwhich the moisture vapor diffuses from the inside to the outside of theabsorbent articles. The diffusion mechanism is not very effective inremoving moisture vapor. Thus, when the absorbent article is loaded withlarge amount of liquids, such as urine, the ineffectiveness of thediffusion through a backsheet may result in significantly increasedrelative humidity between the skin of the wearer and the article.

[0006] Another performance parameter of interest for the loaded/wetabsorbent article is its ability to hold the liquid and prevent leakageespecially when the article is subjected to pressure or impact forceapplied by wearer's motion, such as sitting, walking, bending, andfalling. The leakage under impact or pressure becomes a serious problemwhen the absorbent article is loaded with liquids to near its absorbentcapacity. Consequently, it is desirable to have an absorbent articlewhich exhibits a balance of properties—on one hand it is desirable tokeep the relative humidity in the space between the wearer and theabsorbent article (i.e., the “local” environment) in a comfortablerange, typically between about 30% to about 70% and more typicallybetween about 30% to about 50% relative humidity. Further, the absorbentarticle should desirably have the ability to hold liquids withoutleakage, especially when the article is heavily loaded (i.e., at or nearits absorbent capacity). It is also desirable to provide an absorbentarticle which manages the relative humidity level within the “local”(i.e., the space between the wearer and the absorbent article)environment by a convective transport mechanism. It is further desirableto provide an absorbent article having a carefully designed combinationof chassis elements such that the “local” conditions (e.g., relativehumidity, skin temperature) are optimized for maintaining or improvingskin health.

[0007] Typically, to reduce the humidity level within the space betweenthe absorbent article and the wearer's skin, breathable polymer filmshave been used as the outer cover for the absorbent article. Thebreathable films are typically constructed with micropores to providesubstantial liquid impermeability and some diffusive air/vaporpermeability.

[0008] Other disposable absorbent articles have been designed to providebreathable regions in the form of breathable panels or perforatedopenings in the backsheet or in the core to help ventilate the garment.Articles using perforated components or breathable panels often exhibitexcessive leakage or wet-through of liquids from the article. Moreover,the wearer's movements (e.g., sitting, falling, walking, lying) maysubject the absorbent article to physical forces, such as impact,compression, bending and the like, which may lead to increased leakageand wet-through. The leakage/wet-through problem becomes more severeunder higher impact or pressure, heavy discharges and/or extended weartime.

[0009] Alternatively, multi-layered backsheets or outer covers have beenused to address the wet-through problem. For example, breathablematerials such as a fibrous textile or a nonwoven web have been used inthe outer cover, either alone or in laminates with the microporous film.The relatively open structures of such materials allow air or vapor todiffuse through easily. The laminates may provide improved liquidimpermeability and diffusive air/vapor permeability. The materials maybe treated to further improve the liquid impermeability. However, thelaminates still do not provide satisfactory protection against wetthrough under impact and/or sustained pressure. Further, the transportof air or vapor through the laminates via a diffusive mechanism is notas effective as the transport via a convective mechanism.

[0010] An alternative approach to the wet-through problem is to improvethe absorbent material such that little or no liquid comes into contactwith the backsheet, thereby preventing wet-through. This is typicallyachieved by increasing the amount of absorbent material in the article.However, this approach may lead to an increase in thickness of thearticle and a decrease in comfort as well as a decrease in vapor/airpermeability through the article.

[0011] Another approach to the wet-through problem is to place formedfilms between the core and the backsheet. Formed films having aperturesin the shape of slanted cones are disclosed in PCT publications WO99/39672, WO 99/39673 and WO 99/39674. However, after compaction orsustained pressure, these formed films fail to maintain their formedshape; consequently, they fail to provide the desired balance ofproperties. The compaction or sustained pressure condition may occurbefore consumer use (e.g., during packaging, shipping, and storage), orduring use (e.g., when the wearer sits or falls on the absorbentarticle).

[0012] Therefore, it is desirable to have absorbent articles thatprovide consumer comfort, in terms of reduced relative humidity withinthe absorbent article at a desirable overall thickness, and stillachieve satisfactory wet-through protection.

[0013] It is also desirable to provide absorbent articles which managethe relative humidity within the space between the article and thewearer's skin to maintain good skin health. Further, it is desirable tomanage the relative humidity within the absorbent article by aneffective convective transport mechanism, and, optionally some degree ofdiffusive transport mechanism may be incorporated as well.

[0014] Additionally, it is desirable to provide absorbent articleswherein an optimal local i.e., within the space between the article andthe wearer's skin) condition for skin health and wearer comfort isachieved by careful designs of components of the article. Specifically,it is desirable to provide an absorbent barrier structure having thedesired wet-through protection and air/vapor permeability. Further, theabsorbent barrier structure has a desirable thickness for wearercomfort.

[0015] It is desirable to provide absorbent articles comprising abarrier absorbent structure that can be exposed to compact and/orsustained pressure conditions for at least 24 hours withoutsubstantially degrading its performance, such as air permeability,liquid impermeability and resistance to leakage under impact orsustained pressure.

SUMMARY OF THE INVENTION

[0016] The present invention relates absorbent articles with improvedprotection and comfort by use of an absorbent barrier structure. Theabsorbent article of the present invention may comprise an absorbentcore and an absorbent barrier structure, wherein the absorbent barrierstructure may have a hydrohead value of at least about 10 mBars, aconvective air permeability of at least about 10 Darcy/mm, and a liquidimpact transmission (LIT) value of less than about 20 grams per squaremeters.

[0017] In one embodiment, the absorbent barrier structure may compriseone barrier layer disposed adjacent to the garment-facing surface of theabsorbent core, and one reservoir layer disposed adjacent to thegarment-facing surface of the barrier layer. In another embodiment, anadditional barrier layer may be added to the opposite surface of thereservoir layer. In a further embodiment, the absorbent article mayinclude a dampness management layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is partially broken top plan view of an absorbent articlecontaining the absorbent barrier structure of the present invention;

[0019]FIG. 2A is a cross sectional view of an absorbent barrierstructure of the present invention which has a barrier layer and areservoir layer;

[0020]FIG. 2B is a cross sectional view of an absorbent barrierstructure of the present invention which has a reservoir layer disposedbetween two barrier layers;

[0021] FIGS. 3A-3D are cross sectional views of alternative embodimentsof the absorbent barrier structure of FIG. 2A;

[0022]FIG. 4A is a top plan view of the absorbent barrier structure ofthe present invention which has a barrier zone and a reservoir zone in aside-by-side arrangement;

[0023]FIG. 4B is a top plan view of the absorbent barrier structure ofthe present invention in an alternative arrangement; and

[0024] FIGS. 5A-5B are schematic illustrations of the liquid impacttester before and during the test.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Definitions

[0026] As used herein, the term “absorbent articles” refers to deviceswhich absorb and contain body exudates, and, more specifically, refersto devices which are placed against or in proximity to the body of thewearer to absorb and contain various exudates discharged from the body.Absorbent articles may include diapers, training pants, adultincontinence undergarments, feminine hygiene products, breast pads, andthe like. As used herein, the term “body fluids” or “body exudates”includes, but is not limited to, urine, fecal matter, blood, vaginaldischarges, and sweat.

[0027] The term “disposable” is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter use and, preferably, to be recycled, composted or otherwisedisposed of in an environmentally compatible manner).

[0028] As used herein, the term “zone” refers to a region or an areacomprising a material being physically, chemically, or visuallydistinguishable from surrounding or adjoining materials. Various zonesof materials may include transitional zones between them. The zones maybe positioned in the z-dimension or in the xy-dimension. As used herein,the term “xy-dimension” refers to the plane orthogonal to the thicknessof a member, core or article when the member, core or article is in aflat-out state. The xy-dimension usually corresponds to the length andwidth, respectively, of a structure or an article in a flat-out state.As used herein, the term “z-dimension” refers to the dimensionorthogonal to the length and width of a structure or an article in aflat-out state. The z-dimension usually corresponds to the thickness ofthe structure or article.

[0029] As used herein, the term “unitary structure” refers to astructure comprising materials having different characteristics joinedtogether to form an integral entity such that the materials aresubstantially inseparable physically, and the unitary structure exhibitsproperties resulting from the combination of the materials therein. Thematerials may be arranged in a face-to-face relationship in thez-dimension, or in a side-by-side and/or overlapping relationship in thexy-dimension.

[0030] As used herein, the term “operatively associated” refers to astructure comprising different materials positioned at least in partialcontact with each other in use. The materials are physically separableand each exhibits properties that can be measured individually. Thematerials may be arranged in a face-to-face relationship in thez-dimension, or in a side-by-side and/or overlapping relationship in thexy-dimension.

[0031] As used herein, the term “bonded” or “joined” refers to differentmaterials being attached in at least a portion thereof. The attachedportion may be random or may have a pattern such as stripes, spirals,dots, and the like. The attached portion may be located at theperipheries, in the surface area (continuously or discontinuously), orboth. Suitable attachment means known in the art may be used, includingbut not limited to adhesives, heat, pressure, crimping, ultrasonic,chemical (via hydrogen bonds or other cohesive forces), mechanical(e.g., fasteners, entanglements), hydraulic, vacuum and combinationsthereof.

[0032] As used herein, the term “composite structure” refers to amulti-zoned structure wherein the materials comprising the zones may beoperatively associated or bonded. The zones may even be in intimatecontact such that the composite has a unitary structure. Further, thezones may be positioned in a layered (face-to-face) arrangement, or aside-by-side and/or overlapping arrangement

[0033] As used herein, the term “absorbent core” refers to the componentof the absorbent article that is primarily responsible for fluidhandling properties of the article, including acquiring, transporting,distributing and storing body fluids. As such, the absorbent coretypically does not include the topsheet, backsheet or outer cover of theabsorbent article.

[0034] As used herein, the term “nonwoven web” refers to a web that hasa structure of individual fibers which are interlaid to form a matrix,but not in an identifiable repeating manner. Nonwoven webs may be formedby a variety of processes known to those skilled in the art, forexample, meltblowing, spunbonding, wet-laying, air-laying, and variousbonding-carding processes.

[0035] The present invention relates to absorbent articles with improvedprotection and comfort by use of an absorbent barrier structure. This isachieved by the selection of individual components meeting specificrequirements such that the combination thereof provides the absorbentarticles with the desired performance.

[0036] A typical absorbent article of the present invention may comprisean air/vapor permeable, liquid impermeable outer cover, a liquidpermeable bodyside liner or topsheet, an absorbent core between theouter cover and the bodyside liner, and an absorbent barrier structurepositioned between the outer cover and the absorbent core.

[0037] The absorbent barrier structure of the present invention balancesthe properties of convective air flow and absorptive barrier property.The convective air flow property is effective in reducing the relativehumidity within the space between the absorbent article and the wearer'sskin. The combination of liquid absorption and the liquid barrierproperty provides protection against the wet-through problem, and isespecially beneficial when the absorbent article is under impact and/orsustained pressured conditions.

[0038] The absorbent barrier structure is a composite structure havingat least one barrier zone and at least one reservoir zone. The barrierzone is resistant to liquid penetration so that the outflow of liquidsfrom the absorbent core is substantially slowed or retarded to allowadditional time for the absorbent core to acquire, distribute and retainthe liquids to its full absorbent capacity. Suitable materials for thebarrier zone should have a hydrohead value of at least about 10 mBars.The reservoir zone absorbs and retains any errant liquid that escapesboth the core and the barrier zone, and thus, provides added protectionagainst wet-through. The zones of the absorbent barrier structureprovide a combination of properties, which effectively protect againstthe wet-through problem, even under extreme conditions, such as impactor sustained pressure.

[0039] The following detailed description of the absorbent barrierstructure of the present invention is in the context of a disposablediaper. However, it is readily apparent that the absorbent barrierstructure of the present invention is also suitable for use in otherabsorbent articles such as feminine hygiene products, training pants,incontinence articles, and the like. It is also apparent that theabsorbent barrier structure of the present invention is suitable for usein other hygiene or health care products, such as bandages, dressings,wipes, bibs, surgical drapes, surgical gowns, and the like.

[0040] The Barrier Structure or the Absorbent Barrier Structure

[0041] The present invention provides a barrier structure which allowsconvective transport of air or water vapor though this structure.Particularly, the structure of the present invention achieves thedesirable convective air flow capacity without sacrificing the barrierprotection against wet-through. When the barrier structure is includedin an absorbent article, the resulting absorbent article shows effectivereduction of the relative humidity in the space between the absorbentarticle and the wearer. Consequently, the barrier structure reducesincidents of skin irritation and/or rash and improves skin health andwearer comfort.

[0042] Convective transport capacity is different from the diffusivetransport capacity. The convective transport is driven by a gas or airpressure differential and is typically at a much higher transport ratethan the diffusive transport, which is driven by random molecularmovements. A typical example of diffusive transport includes themoisture migration through the pores of a microporous films such asthose known in the art as the backsheet materials, or through themolecular structure of a nonporous monolithic film such as that madefrom HYTREL® (available from DuPont, Wilmington, Del.). Convectivetransport, on the other hand, is directed by the air pressuredifferential between the inside and the outside of the article. Thoughthe local pressure (i.e., the local pressure within the space betweenthe article and the wearer) and the pressure of the environment (i.e.,outside the article) are substantially the same, small changes in thelocal pressure may lead to convective air/vapor flow towards the outsideof the article. Factors that may lead to convective transport include,but are not limited to, movements by the wearer, small pressure and/ortemperature differential between the local and the outside environment,and the like.

[0043] With the advances made to absorbent articles using elasticmaterials and elastic components, the absorbent articles now provide atighter seal (i.e., less gapping) against the wearer's body to minimizefluid leakage to the outside. Consequently, the convective air flowthrough the gaps is substantially reduced, leading to a humid and hotlocal environment. While absorbent cores typically have some airpermeability; the air permeability typically is reduced when the coresabsorb liquid (i.e., become loaded). The loaded cores can be vented(i.e., made air permeable) relatively easily, typically by ventingmeans, such as holes, baffles, and the like. Alternatively, openness ofthe core structures can be achieved by selected arrangements ofpermeable materials.

[0044] These vented or open-structured cores generally require a leakageprotection component, which is typically a microporous film backsheet ora relatively thick nonwoven fabric that provides liquid impermeabilityand/or leakage protection. However, these liquid impermeable componentsmay reduce the air permeability of the article. In contrast, the barrierstructure of the present invention allows the convective air flowthrough the structure itself without sacrificing leakage protectionproperty.

[0045] In some embodiments, the barrier structure of the presentinvention also provides liquid absorbency and good liquid retentioncapability. Thus, it is also an absorbent barrier structure. The liquidretention capability is especially beneficial when wearer's motions,such as sitting, falling, lying, bending, walking, may applypressure/forces on the loaded (i.e., wetted with bodily fluids)absorbent body and/or the adjacent absorbent barrier structure and maylead to leakage or wet-through. Thus, when the absorbent barrierstructure is included in an absorbent article, the resulting absorbentarticle not only provides effective convective air flow capacity, butalso provides effective protection against wet-through, even when thearticle is subjected to pressure or impact forces.

[0046] Typically, the absorbent barrier structure is positioned betweenthe absorbent core and the outer cover, preferably adjacent to thegarment-facing side of the absorbent core. The absorbent barrierstructure is a composite structure, which comprises a plurality ofindividual zones of materials that are joined or operatively associatedtogether. Alternatively, the plurality of zones may be combined into aunitary structure such that the individual zones become physicallyinseparable. The individual zones of the absorbent barrier structure maybe coextensive or non-coextensive, depending on the requirements of theabsorbent article. The individual zones may be joined by attachmentmeans such as those well known in the art.

[0047] In some embodiments, a member is directly bonded to the othermember by affixing the member directly to the other member. In otherembodiments, a member is indirectly secured to the other member byaffixing one member to intermediate member(s), which in turn are bondedto the other member. For example, the zones may be bonded together by auniform continuous layer of adhesive, or an array of separate lines,spirals, or droplets or beads of adhesive. The adhesive may be appliedcontinuously or intermittently. For example, each application of theadhesive spans the length of the absorbent barrier structure and isseparated from one another by a selected distance. The adhesive isapplied to tack the zones together for handling the webs in the assemblyprocess. Preferably, the adhesive is applied to portions of the surfaceof the absorbent barrier structure, leaving sufficient open (i.e., freeof adhesives) surface areas for air/vapor permeability. Alternatively,the adhesive may be applied to modify the liquid impermeability.Typically, the open or adhesive-free surface area is no less than about50%, preferably no less than about 70%, more preferably no less thanabout 80%, and most preferably no less than about 90% of the totalsurface area of the absorbent barrier structure. Suitable adhesives maybe HL-1258 from H. B. Fuller Company of St. Paul, Minn., and H2031F.from Ato-Findley Inc. of Milwaukee, Wis.

[0048] In one embodiment, the adhesive may be applied in one or morestrips along the peripheries of the zones. In another embodiment, theadhesive may be applied in spaced-apart stripes aligned with thelongitudinal centerline of the diaper when it is used in a diaper. Inanother embodiment, the adhesive may be applied to the web in threestripes along the longitudinal centerline of the diaper. Each stripe is22 mm wide (in the lateral direction of the diaper) and the two outerstripes are disposed at or near (about 4 mm from) the longitudinalperipheries.

[0049] The adhesive is typically applied from its softened or meltedstate to the surface of at least one of the materials comprising theabsorbent barrier structure. Typically, the adhesive is heated to atleast above its softening temperature prior to being applied to asubstrate surface. Once applied, the adhesive is allowed to cool andharden/solidify. Various methods for softened or melted stateapplication of adhesives are known. Methods particularly suitable foruse herein include, but are not limited to, spraying, dipping, gravureprinting, and extrusion.

[0050] Alternatively, the attachment means may comprise heat bonding,pressure bonding, ultrasonic bonding, mechanical bonding (via, forexample, entanglements, cohesive forces, electric or static charges),hydraulic needling or any other suitable attachment means orcombinations of these attachment means as are known in the art.

[0051] The individual zones may be arranged in layers, whereinindividual zones are in an operable, intimate contact with at least aportion of the adjacent layer. Such contacts may be random, or may havea regular pattern, such as dots, stripes, and the like. Preferably, eachlayer is connected to at least a portion of an adjacent layer of theabsorbent barrier structure by a suitable bonding and/or attachmentmeans. In another embodiment, the individual zones may be arranged in anoperable, intimate contact along at least a portion of its peripherieswith the adjacent layer of the absorbent barrier structure.

[0052] The absorbent barrier structure of the present invention may beconstructed to have a convective air permeability of at least about 1Darcy/mm, preferably at least about 10 Darcy/mm, more preferably atleast about 30 Darcy/mm, and most preferably at least about 50 Darcy/mm.Convective air permeability is especially effective in removing moisturevapor from inside the absorbent article, resulting in a lower humidityin the local environment next to the skin.

[0053] Though the liquids are mainly absorbed by the absorbent core, theabsorbent barrier structure provides additional leakage protectionagainst errant liquids that are not absorbed by or are released from theabsorbent core. Thus, the absorbent barrier structure of the presentinvention preferably has at least some liquid absorbency.

[0054] Liquid absorbency may vary, depending on the materials used inthe absorbent barrier structure, the surface tension of the liquid beingtested for absorbency, and the contact angle between the test liquid andthe material. An absorbent barrier structure suitable for use hereintypically has an absorbency (as measured by Test Method G using a 0.2 wt% Triton® solution) of at least about 1 g/g, typically from about 1 toabout 100 g/g, preferably from about 5 to about 50 g/g, more preferablyfrom about 10 to about 30 g/g.

[0055] Further, the absorbent barrier structure of may also have aliquid retention capability, in order to provide the additional leakageprotection, especially under impact and/or sustained pressureconditions. The absorbent barrier structure may have a liquid impacttransmission value (as measured by Test Method C) of less than about 20g/m², preferably less than about 15 g/m², more preferably less thanabout 10 g/m², and most preferably less than about 6.5 g/m².

[0056] Also related to the leakage protection performance, it isdesirable that the absorbent barrier structure has a certain degree ofresistance to liquid penetration. Thus, the absorbent barrier structuremay have a hydrohead value (as measured by Test Method B) of at leastabout 10 mBars, preferably at least about 30 mBars, more preferably atleast about 50 mBars, and most preferably at least about 75 mBars. Insome embodiments, the absorbent barrier structure may have a hydroheadvalue in the range from about 30 to about 100 mBars.

[0057] It is also desirable that the absorbent barrier structureprovides leakage protection in terms of a static liquid transmissionvalue (measured according to Test Method D). In this respect, theabsorbent barrier structure of the present invention has a static liquidtransmission value of less than about 45 g/m², preferably less thanabout 30 g/m², more preferably less than about 20 g/m², and mostpreferably less than 13 g/m², at 15 minutes after impact. Further, theabsorbent barrier structure of the present invention has a static liquidtransmission value of no more than about 50 g/m², preferably no morethan about 35 g/m², more preferably no more than about 20 g/m², at 60minutes after impact.

[0058] In another aspect, after the absorbent barrier structure has beensubjected to the compaction condition such as that described below inthe Test Method F, it does not suffer substantial changes in barrierproperties. The structural integrity during compaction and recoveryafter compaction are desirable for practical purposes. The absorbentarticles are typically compacted into a package for shipping andstorage. When the articles are eventually removed from the compactionfor the intended use, the material or structure that fails to recover toits pre-compaction state may fail to provide the properties it wasoriginally designed for. Thus, the absorbent barrier structure of thepresent invention desirably has a post-compaction air permeabilitydecrease of no more than 35%, preferably no more than 25% decrease andmost preferably no more than 15% decrease, compared to itspre-compaction air permeability. In a preferred embodiment, theabsorbent barrier structure has the post-compaction air permeability asdisclosed above, after 7 days, preferably after 30 days, more preferablyafter 90 days.

[0059] The thickness and basis weight of the absorbent barrier structuremay vary, depending on the materials used, the properties desired, theintended use, the construction, and the like. For example, thicknessand/or basis weight may affect the diffusive breathability and/or theconvective air permeability between the interior of an article and theoutside, the absorbency and/or leakage protection of the article, thefit of the article to the wearer's body, the wearer's comfort, and likeeffects that typically relate to thickness of a structure. Typically,the absorbent barrier structure of the present invention intended foruse in an absorbent article has a thickness of less than about 1.5 mm,preferably less than about 1.2 mm, and more preferably less than about1.0 mm. The thickness of the absorbent barrier structure suitable foruse in an absorbent article should also have a minimal thickness greaterthan about 0.1 mm, preferably greater than about 0.2 mm. Further, theabsorbent barrier structure of the present invention suitable for use inan absorbent article typically has a basis weight in the range of fromabout 20 gsm (g/m²) to about 200 gsm (g/m²), preferably from about 30gsm (g/m²) to about 150 gsm (g/m²), more preferably from about 40 gsm(g/m²) to about 120 gsm (g/m²), and most preferably from about 50 gsm(g/m²) to about 100 gsm (g/m²).

[0060] The absorbent barrier structure typically comprises two zones: abarrier zone and a reservoir zone. The barrier zone is “substantiallyimpermeable” to liquids, including water, urine, menses, and otherbodily fluids. The term “substantially impermeable” means that thebarrier zone exhibits a resistance to liquid penetration but does notnecessarily eliminate liquid wet-through. In other words, it is possiblefor liquid to penetrate and flow through the barrier zone under certainconditions, such as under impact force, under high applied pressure, orunder sustained (i.e., continuously applied) pressure for a period oftime. The reservoir zone is liquid absorbent. When the reservoir zone ispositioned adjacent to the barrier zone, any wet-through and/or leakagefrom the barrier zone may be absorbed by the reservoir zone. Inaddition, the reservoir zone may also absorb errant liquids from theabsorbent core. Thus, the combination of the barrier zone and thereservoir zone achieves the unique balance of properties that, whenexposed to liquids, the barrier zone provides a resistance to liquidwet-through, and the reservoir zone absorbs any errant liquids thatbreak through the resistance of the barrier zone. That is, the absorbentzone provides the added protection against the liquid wet-throughproblem. When the absorbent barrier structure of the present inventionis positioned adjacent to a loaded absorbent core, it provides theadditional protection against wet-through, particularly when the liquidloading level is high and/or the loaded absorbent core is under asudden, high impact force or sustained forces/pressure.

[0061] This additional wet-through protection is especially beneficialfor absorbent articles used in high liquid loading applications (e.g.,diapers, training pants, pull-on diapers, or adult incontinenceproducts). The wet-through protection is also beneficial when theabsorbent articles are subjected to sudden impact or sustained pressure(e.g., when babies or adults fall, sit down, roll, sleep).

[0062] The absorbent barrier structure of the present invention is alsobeneficial when the absorbent core is subjected to gushes of liquids.The resistance to liquid wet-through provides by the barrier zone servesto temporarily slow down the gushes of liquids, possibly pooling theliquids at the interface between the absorbent core and the barrierzone. The slowed flow and pooling provide the additional time for theabsorbent core to acquire and distribute the liquids to other regions ofthe core beyond the point of insult. Consequently, the absorbent coremay achieve its full absorbent capacity.

[0063] Exemplary absorbent barrier structure of the present inventionare illustrated in the following figures. FIG. 2A is a cross sectionalview of an embodiment of the absorbent barrier structure of thisinvention. The absorbent barrier structure 10 comprises a barrier layer12 and a reservoir layer 14. In another embodiment, as shown in FIG. 2B,an additional barrier layer 16, may be disposed on the other side of thereservoir layer 14 such that the reservoir layer 14 is sandwichedbetween the barrier layers 12 and 16. The first and the second barrierlayers may be made of identical or different (in terms of constructionof the web, basis weight, thickness, porosity, fiber denier, material,and the like) fibrous webs.

[0064] Various arrangements of the barrier zone and the reservoir zoneare shown in FIGS. 3A-3D. In FIG. 3A, multiple barrier zones 12 andreservoir zones 14 are arranged in a side-by-side relation, wherein thebarrier zones 12 and the reservoir zones 14 are preferably stripes. InFIG. 3B, the barrier zone 12 is a continuous web and the reservoir zone14 is disposed adjacent thereto in a discontinuous pattern, such asstripes, circles, ellipses, squares, and the like. In FIG. 3C, thereservoir zone 14 is a continuous web and the barrier zone 12 isdisposed adjacent thereto in a discontinuous pattern, such as stripes,circles, ellipses, squares and the like. In FIG. 3D, the discontinuousbarrier zones 12 overlap at least partially with the discontinuousreservoir zones 14, and each may have the shape of stripes, circles,ellipses, squares, and the like.

[0065] In all of the embodiments illustrated in FIGS. 2A-3D, at least aportion of the barrier zone is positioned adjacent to the garment-facingside of the absorbent core. In one embodiment, the absorbent barrierstructure may be substantially coextensive with the absorbent core.Alternatively, the absorbent barrier structure may be stripes or patchesthat extend only to portions of the absorbent core. In anotherembodiment, the absorbent barrier structure may extend beyond the outeredges of the absorbent core or only through the length and width of thecentral portion of the absorbent core. In one embodiment, the barrierzone and the reservoir zone are arranged in a layered relation, whereinthe barrier layer is disposed immediately adjacent to the garment-facingside of the absorbent core. Configurations in which the barrier zone hasat least the same length and width of the absorbent core are desirable.Furthermore, the reservoir zone need not have the same dimensions as thebarrier zone.

[0066] The Reservoir Zone

[0067] The reservoir zone desirably absorbs, spreads and retains liquidssuch as urine, blood and other body exudates. The reservoir zone has agarment-facing surface, a body-facing surface, front and rear edges, andside edges. The reservoir zone absorbs and retains the errant liquidsthat escape from other components such as the absorbent core and thebarrier zone. Thus, the reservoir zone provides additional protectionagainst wet-through.

[0068] The thickness and basis weight of the reservoir zone may vary,depending on the materials used, the properties desired, the intendeduse, the openness of the construction, and the like. Specifically, thethickness of the reservoir zone may affect the air/gas permeability, theabsorbency and/or leakage protection of the barrier absorbent structure,as well as the comfort and fit of the absorbent article, and likeeffects typically related to the thickness of a structure. Thus, thereservoir zone typically has a thickness of less than about 1.5 mm,preferably less than about 1.0 mm, and more preferably less than about0.8 mm. The reservoir zone may desirably have a minimal thickness toprovide for adequate absorbency and structural integrity. The minimalthickness of the reservoir zone is typically no less than about 0.2 mm,preferably no less than about 0.1 mm, more preferably no less than 0.05mm, and most preferably no less than 0.02 mm. Further, the basis weightof the reservoir zone is typically in the range from about 5 gsm (g/m²)to about 120 gsm (g/m²), preferably from abut 10 gsm (g/m²) to about 100gsm (g/m²), and more preferably from about 30 gsm (g/m²) to about 80 gsm(g/m²).

[0069] When compared to the absorbent core, the reservoir zone absorbsfluids more readily (i.e., a faster fluid uptake) and releases fluidsmore readily. The reservoir zone typically has an absorbency of at leastabout 1 g/g, preferably at least about 5 g/g, more preferably at leastabout 10 g/g, based on Test Method G and using 0.2 wt % TRITON® as thetest fluid. The absorbency of the reservoir zone is preferably less thanabout 30 g/g, and more preferably less than about 20 g/g. Further, thereservoir should have an absorbency that is less than that of theabsorbent core by at least about 20%, preferably by about 30%.

[0070] The reservoir zone may desirably have an open structure such thatits air or gas permeability is at least equal to that of the resultingabsorbent barrier structure. The convective air/vapor permeability ofthe reservoir zone is typically at least about 1 Darcy/mm, preferably atleast about 10 Darcy/mm, more preferably at least about 30 Darcy/mm, andmost preferably at least about 50 Darcy/mm.

[0071] Further, the openness of the structure may enhance absorbency byholding or absorbing the fluids in the interstitial spaces in the openstructure. Suitable open structures may include fibrous webs (e.g.,woven or nonwoven webs); absorbent foams (e.g., porous or reticulatedfoams); fibrous wads; and the like.

[0072] In one embodiment, the reservoir zone is made of fibrous webs.The fibrous webs constituting the reservoir zone need not necessarilycomprise absorbent fibers, so long as the webs are absorbent. Thus, theconstituent fibers may simply be hydrophilic fibers and have noabsorptive capacity by themselves.

[0073] In one embodiment, the reservoir zone is made of primarilycellulosic fibers which are primarily hydrogen bonded to one another.Cellulosic fibers may be natural or processed, and may be chemicallystiffened, modified or cross-linked. Processed cellulosic fibers mayinclude commercially available fibers made of regenerated cellulose orderivatized cellulose, such as Rayon. In another embodiment, thereservoir zone may comprise at least about 70 wt % of cellulosic fibers,preferably at least about 80 wt % and more preferably at least about 90wt %. Alternatively, the reservoir zone may comprise from about 95 to100 wt % cellulosic fibers.

[0074] In another embodiment, the reservoir zone may be in the form of asingle or multi-ply tissue; a creped tissue; a tissue wadding; or anairfelt mat. High wet strength tissue may also be used as the reservoirzone. In another embodiment, the reservoir zone may be of any formhaving an open structure whereby the bodily fluids are held or absorbedin the fine interstitial spaces in the open structure. Further,inter-ply spaces and surface textures may provide additionalinterstitial, liquid holding capacitites, which enhance the absorbencyof the reservoir zone.

[0075] The reservoir zone may include supplemental chemical bondingagents that are well known in the art. For example, the reservoir zonemay include a chemical bonding agent such as vinyl acrylic copolymers,polyvinyl acetate, crosslinkable polyamides, polyvinyl alcohol and thelike. Additionally, wet strength resins and/or resin binders may beadded to improve the strength of the cellulosic web. Useful binders andwet strength resins include commercially available resins, for example,KYMENE®, available from Hercules Chemical Company and PAREZ® availablefrom American Cyanamid, Inc. Crosslinking agents and/or hydrating agentsmay also be added to the pulp mixture to reduce the degree of hydrogenbonding if an open or loose fibrous web is desired. An exemplarydebonding agent is available from Quaker Chemical Company, Conshohocken,Pa., under the trade name Quaker 2008. The reservoir zone may contain nomore than 5 weight percent and optionally may contain no more than about2 weight percent of the chemical bonding agent. The reservoir zonetypically comprises a high wet strength tissue. Alternatively, thereservoir zone may comprise a synthetic fibrous web. The reservoir zonemay be bonded, such as with adhesives, to the barrier zone or othercomponents of the diaper construction.

[0076] Suitable materials for the reservoir zone may comprise aprimarily cellulosic fibrous web, such as commercially availableconsumer paper towels BOUNTY®, manufactured by The Procter & GambleCompany, Cincinnati, Ohio, or HI-DRY®, manufactured by TheKimberly-Clark Corporation.

[0077] Suitable fibrous webs may have a single-ply or a multi-plyconstruction. As used herein, the term “ply” means individual webs beingdisposed in a substantially contiguous, face-to-face relationship,forming a multiple layered web. Further, a single web may form twoplies, for example, by folding on itself. In a multi-ply construction,the individual webs are at least partially joined, typically via pointbonding, with or without adhesives.

[0078] It is found that the multi-ply construction provides higherresistance to liquid breakthrough than a single-ply construction on aunit weight basis (gram per square meter). Further, the absorbency of atwo-ply fibrous web is at least double that of the single-ply fibrousweb, on a unit weight basis. Without being bound by theory, it isbelieved that the interstitial spaces (i.e., structural voids) betweenthe plies provide additional liquid holding space, consequently, ahigher absorptive capacity. Furthermore, post-treatments of thecellulosic web, including, but not limited to, aperturing, creping,embossing, or otherwise texturizing, increase the absorbency of the web.Fibrous webs having apertured or texturized surfaces show higherabsorptive capacity, possibly due to the microvoids and/or interstitialspaces created by the treatments. In one embodiment, the reservoir zoneis made from a fibrous web having a construction of at least two pliesand a texturized surface. Additionally, certain additives, such asdebonding agents, may also increase the absorbency of the web byreducing the inter-fiber bondings (e.g., hydrogen bonds betweencellulosic fibers), thus, loosening the compacted fibrous network in thewebs. The openness of the resulting web provides more interstitialspaces to hold liquids and enhances the absorbency of the web.

[0079] In an alternative embodiment, other types of wettable and/orhydrophilic fibrous materials may be used to form the reservoir zone ofthe absorbent barrier structure. Exemplary fibers include naturallyoccurring organic fibers made from intrinsically wettable material, suchas cellulose or processed cellulose fibers, including regenerated orderivatized cellulose fibers commercially available as Rayon® fiber,Viscose® fibers; synthetic fibers made from inherently wettablethermoplastic polymers, such as polyesters, polyamides, theircopolymers, polyvinyl alcohols, polyalkylene oxides, and mixtures ofthese polymers; and synthetic fibers made from a nonwettablethermoplastic polymers, such as polyethylene, polypropylene,polybutylene and other polyolefins, which may be hydrophilized byappropriate means. These nonwettable fibers may be hydrophilized bytreatments with surfactants or surface-active agents having suitablehydrophilic functionalities, or by sheathing. These nonwettable fibersmay also become of more wettable by grafting hydrophilic functionalitiesonto the polymer chains. Suitable hydrophilic functionalities include,but are not limited to, acrylic, methacrylic, ester, amide, and mixturesthereof. Combination fibers such as bi-component fibers, sheathedfibers, are also suitable for use herein.

[0080] The reservoir zone may contain additives such as chemical bondingagents, crosslinking agents, wet strength resins, debonding agents,liquid or moisture absorbing agents, odor absorbing agents,antimicrobials, coloring agents, stiffening agents, and mixturesthereof. The liquid or moisture absorbing agents, include, but are notlimited to, clays, silicas, talc, diatomaceous earth, perlite,vermiculite, carbon, kaolin, mica, barium sulfate, aluminum silicates,sodium carbonate, calcium carbonate, other carbonates, superabsorbentpolymers or other osmotic liquid holding agents, and mixtures thereof.

[0081] In one embodiment, the reservoir zone additionally containssuperabsorbent polymers, which are coated onto the fibers, blended intothe fibers in-situ, or are made into fibers or particles.

[0082] The Barrier Zone

[0083] The barrier zone preferably has a “barrier-like” property (i.e.,resistance to liquid wet-through). The barrier property is typicallymeasured by the Test Method B described below. It is desirable that thehydrohead value of the barrier zone should be higher than that of theabsorbent core and of the reservoir zone. The barrier zone materialsuitable for use herein typically exhibits a hydrohead value of at leastabout 10 mBars, preferably at least about 30 mBars, more preferably atleast about 50 mBars, and most preferably at least about 75 mBars. Insome embodiments, the suitable barrier zone has a hydrohead value in therange from about 30 to about 100 mBars.

[0084] It is also desirable that the barrier zone substantially reducesthe air/vapor permeability of the absorbent article. In that respect,the barrier zone typically has a convective air permeability of at leastabout 10 Darcy/mm and preferably at least about 30 Darcy/mm.

[0085] The hydrohead value of a fibrous web increases with finer fiberdiameter, higher fiber density, higher basis weight, or combinationsthereof. Suitable fibrous webs for the barrier zone typically have abasis weight of at least about 2 gsm, preferably from about 5 to about100 gsm, more preferably from about 10 to about 75 gsm, and mostpreferably from about 15 to about 55 gsm.

[0086] The thickness of the barrier zone may vary, depending on thematerials used, the properties desired, the intended use, theconstruction, and the like. Specifically, the thickness of the barrierzone may affect the air/gas permeability, the absorbency and/or leakageprotection of the barrier absorbent structure, as well as the comfortand fit of the absorbent article, and like effects typically related tothe thickness of a structure. Thus, the barrier zone typically has athickness of less than about 1.5 mm, preferably less than about 1.0 mm,more preferably less than about 0.8 mm, and most preferably less thanabout 0.5 mm.

[0087] It has been found that some materials which do not appreciablylimit the air permeability of the absorbent article in the dry statewill significantly decrease the air permeability of the article when theabsorbent core becomes loaded with liquids. Thus, suitable materials foruse in the barrier zone should allow sufficient water vaportransmission, when the absorbent article is in a dry state. It isdesirable that the air/water vapor permeability of the absorbent articledoes not change substantially from that of an equivalent diaper withoutthe barrier zone material. However, when the absorbent core becomesloaded from absorbing liquids discharged from the body, the barrier zonemay lower the air/vapor permeability of the absorbent article (relativeto an equivalent article without a barrier zone), thereby reducing oreliminating the dampness which may develop on the garment side of theouter cover.

[0088] In order to provide the desired hydrohead value or the“barrier-like” property, suitable materials are preferably hydrophobic,though this is not a required characteristic. Exemplary hydrophobicpolymeric materials are typically polyolefins, such as polyethylene,polypropylene, polybutylene and copolymers thereof. Materials that arenot hydrophobic, such as polyamides, polyesters, polyalkylene oxides,polyvinyl alcohols, may be treated by suitable hydrophobic agents toachieve the desired hydrophobicity. Additionally, the reservoir layermay also be treated on at least one surface to improve itshydrophobicity, hence, its barrier property.

[0089] Treatments for improved hydrophobicity may include chemical,radiation, plasma or combinations thereof. Further, the surfacetreatment to modify the surface characteristics may be accomplished by acoating on the surface, by pre-blending with a hydrophobic agent or byincorporating a hydrophobic agent in-situ, which blooms to the surfaceby further processing.

[0090] In one embodiment, fluorocarbon treatment of the web material mayprovide the desired hydrophobicity such that the web exhibits thedesired water resistance characteristics, measured, for example, by TestMethod B. In another embodiment, fluorocarbon treatment using plasma orlike technology may provide a very thin, hydrophobic coating such thatthe air permeability of the treated web is substantially unchanged. Ifdesired, the treatment may be applied to only portions of the substratesurface. These treatments may be applied to different components of theabsorbent article, including but are not limited to the barrier zone,the reservoir zone, the outer cover, or other diaper components.Suitable substrate materials for this treatment include, but are notlimited to, nonwoven webs, cellulosic webs, thermoplastic films,modified/processed films (e.g., formed, apertured) and the like.Exemplary surface treatments using fluorocarbons are described in U.S.Pat. No. 5,876,753, issued to Timmons et al. on Mar. 2, 1999; U.S. Pat.No. 5,888,591 issued to Gleason et al. on Mar. 30, 1999; U.S. Pat. No.6,045,877 issued to Gleason et al. on Apr. 4, 2000; PCT PatentApplication 99/20504 by D'Agostino et al., published on Mar. 7, 1999;PCT Publication 00/14296 by D'Agostino et al., published on Mar. 16,2000; the disclosures of each is hereby incorporated by reference.

[0091] Other surface coating methods using silicones or fluoro chemicalsare known in the art and may be used herein. The conventional coating orsurface treatment methods typically fill the voids within the web, andthus, lowers its air permeability. Coating methods to providehydrophobicity to the substrate without the decrease in air permeabilitycan be found in U.S. Pat. No. 5,322,729 and PCT Publication WO 96/03501,the disclosure of each is hereby incorporated by reference.

[0092] The barrier zone may comprise fibrous web materials such asnonwoven webs including, but not limited to, meltblown (MB) webs;spunbond (SB) webs, particularly fine fiber spunbond webs such as thosehaving fiber deniers of about 2 or less; composite webs having layers ofmeltblown and spunbonded fibers, commonly known as MS nonwovens, and SMSnonwovens; bonded and carded webs; air laid webs; hydro-entangled webs;knitted webs; and woven webs.

[0093] Nonwoven webs having the desired combination of high liquidresistance and high air permeability are typically made by the meltblowing process. Nonwoven webs comprising low denier fibers and/oruniform distribution of fine fibers are desirable.

[0094] In one embodiment, the barrier zone comprises a meltblown web ofpolypropylene fibers having a basis weight of from about 4 to about 80g/m², preferably from about 6 to about 70 g/m², more preferably fromabout 8 g/m² to about 50 g/m², and most preferably from about 10 toabout 30 g/m².

[0095] The meltblown fibers typically have an average diameter in therange of less than about 20 microns, preferably less than about 10microns. Most typically, the meltblown fibers have an average fiberdiameter in the 5 to 10 microns range. Also suitable for use herein arenanofibers having an average fiber diameter in the range of less thanabout 500 nanometers, preferably less than about 300 nanometers, andmore preferably less than about 150 nanometers. Exemplary nonwoven websmade from nanofibers (having average fiber diameters from about 10 toabout 100 nanometers) are available from E-Spin Technologies(Chattanooga, Tenn.).

[0096] While the strength of the meltblown nonwoven web generallydecreases with decreasing fiber denier, the strength can be improved bylamination with a reinforcing scrim or web such as tissues, papertowels, or spunbonded nonwoven webs. Any conventional lamination processmay be used, including adhesive bonding, thermal boning, ultrasonicbonding, calendaring, needling, and combinations thereof. However, thelamination process should be carefully exercised to minimize adverseeffects on the air permeability of the resulting laminate. In oneembodiment, the microfiber nonwoven web may be integrally laminatedduring the manufacture by direct melt blowing onto another reinforcingscrim or web.

[0097] The fibrous barrier zone may comprise a single web or multiplelayers of webs which collectively have the desired characteristics.However, when using multiple layers of webs, it is desirable that theyare juxtaposed without being point bonded across a substantial surfacearea of the zones or otherwise bonded in a manner which wouldsubstantially limit the breathability of the zones. When joining thebarrier zone to the absorbent core and/or the reservoir zone, it isdesirable that the breathability of the article is maintained. In thisregard, it may be desirable that the barrier zone be attached to othercomponents the absorbent article (such as the absorbent core, thereservoir zone) primarily at the peripheries of the barrier zone. Themultiple zones can be joined by heat, pressure, ultrasonic, adhesive orby other means known in the art.

[0098] The barrier zone may contain additives such as chemical bondingagents, crosslinking agents, liquid or moisture absorbing agents, odorabsorbing agents, antimicrobials, coloring agents, stiffening agents,and mixtures thereof. The liquid or moisture absorbing agents,including, but not limited to, clays, silicas, talc, diatomaceous earth,perlite, vermiculite, carbon, kaolin, mica, barium sulfate, aluminumsilicates, sodium carbonate, calcium carbonate, other carbonates,superabsorbent polymers or other osmotic liquid holding agents, andmixtures thereof.

[0099] Absorbent Article Components

[0100]FIG. 1 is a partially broken top plan view of a diaper 20containing the absorbent barrier structure 10 of the present invention.The diaper 20 is in a flat-out state with portions of the structure cutaway to more clearly show the construction of the diaper 20. Thegarment-facing surface of the diaper 20 is oriented away from theviewer.

[0101] As shown in FIG. 1, the diaper 20 comprises a liquid pervioustopsheet 24; a dampness management means 26; an absorbent core 28, whichis positioned between at least a portion of the topsheet 24 and theouter cover 22; an absorbent barrier structure 10 positioned between theabsorbent core 28 and the outer cover 22; side panels 30; elasticizedleg cuffs 32; elastic waist features 34; and a fastening system 40. Anabsorbent barrier structure 10 of the present invention is disposedadjacent to the absorbent core 28 on the garment facing surface of theabsorbent core 28.

[0102] Diaper 20 is shown in FIG. 1 to have a front waist region 36, arear waist region 38 opposed to the front waist region 36 and a crotchregion 37 located between the front and the rear waist regions. Theperipheries of the diaper 20 are defined by the outer edges of thediaper 20 in which the longitudinal edges 50 run generally parallel tothe longitudinal centerline 100 of the diaper 20 and end edges 52 runbetween the longitudinal edges 50 generally parallel to the lateralcenterline 110 of the diaper 20.

[0103] The main body of the diaper 20 comprises at least the absorbentcore 28, the topsheet 24, and preferably, though not necessarily, thedampness management means 26. An outer cover 22 forms the chassis, ontowhich other components of the diaper 20 are added to form the unitarystructure of the diaper.

[0104]FIG. 1 shows an embodiment of the diaper 20 in which the topsheet24 and the dampness management means 26 have length and width dimensionsgenerally no smaller than those of the absorbent core 28 and theabsorbent barrier structure 10. The topsheet 24 and the dampnessmanagement means 26 may extend to the peripheries of the diaper 20. Inanother embodiment, the absorbent barrier structure 10 may extend beyondthe edges of the absorbent core 28 to the peripheries of the diaper 20.

[0105] While the components of the diaper 20 may be assembled in variouswell known configurations, preferred diaper configurations are describedgenerally in U.S. Pat. No. 3,860,003 entitled “Contractible SidePortions for Disposable Diaper” issued to Kenneth B. Buell on Jan. 14,1975; U.S. Pat. No. 5,151,092 issued to Buell on Sep. 9, 1992; and U.S.Pat. No. 5,221,274 issued to Buell on Jun. 22, 1993; and U.S. Pat. No.5,554,145 entitled “Absorbent Article With Multiple Zone StructuralElastic-Like Film Web Extensible Waist Feature” issued to Roe et al. onSep. 10, 1996; U.S. Pat. No. 5,569,234 entitled “Disposable Pull-OnPant” issued to Buell et al. on Oct. 29, 1996; U.S. Pat. No. 5,580,411entitled “Zero Scrap Method For Manufacturing Side Panels For AbsorbentArticles” issued to Nease et al. on Dec. 3, 1996; and U.S. Pat. No.6,004,306 entitled “Absorbent Article With Multi-Directional ExtensibleSide Panels” issued to Robles et al. on Dec. 21, 1999; each of which isincorporated herein by reference.

[0106] Topsheet or Body-side Liner

[0107] The topsheet is compliant, soft feeling, and non-irritating tothe wearer's skin. The topsheet material can also be elasticallystretchable in one or two directions. Further, the topsheet is fluidpervious, permitting fluids (e.g., urine, menses, other bodily fluids)to readily penetrate through its thickness. A suitable topsheet can bemanufactured from a wide range of materials such as woven and nonwovenmaterials; apertured or hydroformed thermoplastic films; porous foams;reticulated foams; reticulated thermoplastic films; and thermoplasticscrims. Suitable woven and nonwoven materials may comprise of naturalfibers such as wood or cotton fibers; synthetic fibers such aspolyester, polypropylene, or polyethylene fibers; or combinationsthereof.

[0108] Preferred topsheets for use in the present invention are selectedfrom high loft nonwoven topsheets and apertured film topsheet. Aperturedfilm topsheet typically are pervious to bodily exudates, yetnon-absorbent, and have a reduced tendency to allow fluids to pass backthrough and rewet the wearer's skin. Suitable apertured films includethose described in U.S. Pat. No. 5,628,097, U.S. Pat. No. 5,916,661, EP1,051,958, EP 1,076,539; the disclosure of each is hereby incorporatedby reference.

[0109] Nonwoven materials, such as described in EP 774,242 (Palumbo),which is incorporated herein by reference, generally exhibit high gaspermeability, thus, do not exhibit a significant resistance to air flow.

[0110] Further, suitable tospheet materials for depositing solidexcretions thereon may include nonwovens having apertures, which are atleast in the portions that are aligned with the feces deposition regionof the article. Suitable apertured nonwovens are described in moredetail in EP 714,272 or EP 702,543, and both of which are incorporatedherein by reference. In another embodiment of feces handling articles,such topsheets can be combined with feces handling members e.g.underlying such topsheets, and further described in these applications.

[0111] The material forming the topsheet may be hydrophilic so as tofacilitate fluid transport through the topsheet. Surfactants may beincorporated into the polymeric materials to improve the hydrophilicityof the topsheet, such as is disclosed in EP-A-166,056 and U.S. patentapplication Ser. No. 07/794,745, filed on Nov. 19, 1991, both of whichare incorporated herein by reference. Alternatively, the topsheet may betreated with a surfactant to render the body-facing surface hydrophilic,such as is disclosed in U.S. Pat. No. 4,950,254, which is herebyincorporated by reference.

[0112] Absorbent Core

[0113] The absorbent core may include the following components: (a)optionally, a primary fluid distribution layer; (b) optionally, asecondary fluid distribution layer; (c) a fluid storage layer; (d) otheroptional components, such as a fibrous “dusting” layer.

[0114] The optionally primary fluid distribution layer is typicallydisposed under the topsheet and is in fluid communication with thetopsheet. The topsheet transfers the acquired bodily fluids to theprimary distribution layer to ultimate distribution to the storagelayer. This transfer of fluid through the primary distribution layeroccurs not only in the thickness, but also along the length and widthdirections of the absorbent core. The optionally secondary fluiddistribution layer is typically disposed under the primary fluiddistribution layer and is in fluid communication therewith. Thesecondary fluid distribution layer readily acquires fluid from theprimary distribution layer and transfers it rapidly to the underlyingstorage layer. Thus, the fluid capacity of the underlying storage layermay be fully utilized, especially when gushes of bodily discharge occur.

[0115] The fluid storage layer typically comprises absorbent materialsincluding absorbent gelling materials, which are usually referred to as“hydrogels”, “superabsorbent” “hydrocolloid” materials. Absorbentgelling materials are those materials that, upon contact with aqueousfluids, such as bodily fluids, imbibes such fluids and form hydrogels.These absorbent gelling materials are typically capable of absorbinglarge quantities of aqueous bodily fluids, and further capable ofretaining such absorbed fluids under moderate pressures. These absorbentgelling materials are typically in the form of discrete, nonfibrousparticles. Other forms, such are fibers, foams, sheets, strips, or othermacrostructures, are also suitable for use herein. Suitable absorbentgelling materials in the form of open cell foams may include thosedisclosed in U.S. Pat. No. 3,563,243 (Lindquist), U.S. Pat. No.4,554,297 (Dabi), U.S. Pat. No. 4,740,520 (Garvey), U.S. Pat. No.5,260,345 (DesMarais et al.), all of which are incorporated herein byreference. Improvements of these foams can be found in WO 96/21679, WO96/21680, WO 96/21681, WO 96/21682, WO 97/07832 and WO 98/00085, all ofwhich are incorporated herein by reference.

[0116] The absorbent gelling materials suitable for use herein maycomprise a substantially water-insoluble, slightly crosslinked,partially neutralized, polymeric gelling material. This material forms ahydrogel upon contact with water. Suitable absorbent gelling materialsinclude those disclosed in U.S. Pat. No. 4,654,039, U.S. Pat. No.5,562,646, U.S. Pat. No. 5,599,335, U.S. Pat. No. 5,669,894, each ofwhich is incorporated herein by reference.

[0117] The fluid storage layer may comprise absorbent gelling materialsalone or dispersed in a suitable carrier, homogeneously orinhomogenously, or may comprise of absorbent carrier materials alone.The storage layer may also include filler materials, such as perlite,diatomaceous earth, vermiculite, and the like, which absorb and retainthe fluid, and thus, reduce the rewet-through the topsheet.

[0118] Suitable carrier materials include cellulose fibers, in the formof fluff, tissues or paper. Modified cellulose fibers (e.g., stiffened,chemically treated, crosslinked) may also be used. Synthetic fibers mayalso be used. Suitable synthetic fibers may be made of celluloseacetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (such asOrlon®), polyvinyl acetate, non-soluble polyvinyl alcohol, polyethylene,polypropylene, polyamides (such as Nylon®), polyesters, bi- ortri-component fibers thereof, and mixtures of these materials.Preferably, the fiber surfaces are hydrophilic or are treated to behydrophilic.

[0119] Typically, the storage layer comprises from about 15 to 100 wt %of the absorbent gelling material dispersed in a carrier material.Preferably the storage layer comprises from about 30 to about 95 wt %,more preferably from about 60 to about 90 wt % of the absorbent gellingmaterial. The carrier material typically comprises from about 0 to about85 wt %, preferably from about 5 to about 70 wt %, and more preferablyfrom about 10 to about 40 wt % of the storage layer.

[0120] An optional component for inclusion in the absorbent core is afibrous layer adjacent to, and typically underlying the storage layer.This underlying fibrous layer is typically referred to as a “dusting”layer since it provides a substrate on which to deposit absorbentgelling material in the storage layer during manufacture of theabsorbent core. Further, the “dusting” layer provides some additionalfluid handling capability such as rapid wicking of fluid along thelength of the absorbent core.

[0121] The absorbent core may include other optional components. Forexample, a reinforcing scrim may be positioned within the respectivezones, or between the respective zones, of the absorbent core.Optionally, odor control agents may be included in the absorbent core.Suitable odor control agents include active carbons, zeolites, clays,silicas, and mixtures thereof. The configuration and construction of theabsorbent core may also be varied (e.g., the absorbent core may havevarying caliper zones, a hydrophilicity gradient, a pore size gradient,a superabsorbent gradient, or lower average density and lower averagebasis weight acquisition zones; or may comprise one or more zones orstructures). The total absorbent capacity of the absorbent core should,however, be compatible with the designed loading and the intended use ofthe diaper. Further, the size and absorbent capacity of the absorbentcore may be varied to accommodate wearers ranging from infants throughadults. Suitable absorbent cores include those disclosed in EP1,051,958, EP 797,968 and EP 774,242, each of which is incorporated byreference herein.

[0122] Outer Cover

[0123] The term “outer cover” as used herein means a structural elementpositioned on the garment-facing surface of the absorbent article. Theouter cover typically forms the chassis onto which other components ofthe diaper are added. However, the outer cover may just be a coatinglayer on the garment side of the absorbent article.

[0124] Suitable material for the outer cover typically provide a barrierfunction with respect to liquids (i.e., liquid impervious) whilepreferably allowing air or vapor to flow through (i.e., vaporpermeable). Typically, the outer cover is not the rate limiting elementto gas or vapor transport through the absorbent article. In someembodiments, the outer cover may have a structure that is relativelyopen to allow for convective air or gas permeability. The suitable outercover typically has a moisture vapor transmission rate (MVTR) of atleast about 500 g/m²/24 hrs, more preferably of at least about 1500g/m²/24 hrs, and most preferably at least about 3000 g/m²/24 hrs.Additionally, the outer cover provides a soft, pleasant feel to theskin, either by the material property, or by texturizing or embossingits surface, or both.

[0125] The outer cover may be a single layer of homogeneous ormulti-component material, or a composite of various layers of materials.The outer cover suitable for use herein comprises porous materials suchas an apertured film (e.g., having a plurality of shaped openings orangled capillaries), a knitted web, a porous woven or nonwoven web, afoam, or combinations or laminates thereof. In one embodiment, the outercover comprises nonwoven webs or multi-layered nonwovens such asspunbond/meltblown (SB) nonwoven, spunbond/meltblown/spunbond (SBS)nonwoven.

[0126] The outer cover, or any portion thereof, may be elasticallyextensible in one or more directions. In one embodiment, the outer covermay comprise a structural elastic-like film (“SELF”) web. A SELF web isan extensible material that exhibits an elastic-like behavior in thedirection of elongation without the use of added elastic materials andis described in more detail in U.S. Pat. No. 5,518,801 entitled “WebMaterials Exhibiting Elastic-Like Behavior” issued to Chappell, et al.on May 21, 1996, which is incorporated herein by reference. In alternateembodiments, the outer cover may combine elastomeric components (such asfilms, foams, strands, or combinations thereof) with nonwovens orsynthetic films.

[0127] In another embodiment, the outer cover may be a nonwoven webconstructed to provide the required level of liquid impermeability. Forexample, a nonwoven web of spunbonded or meltblown polymer fibers may betreated, at least partially, with a hydrophobic coating. Exemplarytreatments using fluorocarbons are described in U.S. Pat. No. 5,876,753,issued to Timmons et al. on Mar. 2, 1999; U.S. Pat. No. 5,888,591 issuedto Gleason et al. on Mar. 30, 1999; U.S. Pat. No. 6,045,877 issued toGleason et al. on Apr. 4, 2000; U.S. patent application Ser. No.99/20504 by D'Agostino et al., filed on Mar. 7, 1999; the disclosures ofwhich are hereby incorporated by reference.

[0128] Optionally, the outer cover material may comprise the absorbentand swellable materials described in U.S. Pat. No. 5,955,187 issued toMcCormack et al. on Sep. 21, 1999; or the absorbent and shrinkablematerials described in U.S. patent application Ser. No. 97/22604 byCorzani et al. on Dec. 15, 1997; or the absorbent and differentialstrainable materials described in PCT Publication WO 00/68003 by Dawsonet al.; the disclosures of which are hereby incorporated by reference.

[0129] The absorbent article may comprise an outer cover which isseparated from the absorbent core at least partially by the absorbentbarrier structure of the present invention and is preferably joined tothe absorbent barrier structure and/or the absorbent core by attachmentmeans such as those well known in the art.

[0130] The outer cover may be secured to the absorbent barrier structureand/or the absorbent core by a uniform continuous layer of adhesive, anopen pattern network of filaments of adhesive, or an array of separatelines, spirals, or spots of adhesive, as disclosed in U.S. Pat. No.4,573,986 issued to Minetola et al. on Mar. 4, 1986; U.S. Pat. No.3,911,173 issued to Sprague, Jr. on Oct. 7, 1975; U.S. Pat. No.4,785,996 issued to Ziecker, et al. on Nov. 22, 1978; and U.S. Pat. No.4,842,666 issued to Werenicz on Jun. 27, 1989; the disclosure of each isincorporated herein by reference. Adhesives suitable for use herein aremanufactured by H. B. Fuller Company of St. Paul, Minn. and marketed asHL-1258. Alternatively, the attachment means may comprise heat bonds,pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any othersuitable attachment means or combinations of these attachment means asare known in the art.

[0131] The outer cover material may not significantly lower theconvective air permeability of the absorbent article. More importantly,the combination of the absorbent barrier structure and the outer cover(hereinafter referred to as the “combined structure” or “combination”)provide the desired balance of properties, including, but not limitedto, absorbency, barrier property and convective air permeability.

[0132] The combined structure of the present invention may beconstructed to have a convective air permeability of at least about 10Darcy/mm, preferably at least about 20 Darcy/mm, more preferably atleast about 30 Darcy/mm, and most preferably at least about 50 Darcy/mm.Convective air permeability is especially effective in removing moisturevapor from inside the absorbent article, resulting in a lower humidityin the local environment next to the skin, which reduces incidences ofskin irritation or rash and promotes skin health.

[0133] Further, the combined structure of the present inventionpreferably has a liquid impact transmission value (as measured by TestMethod C) of no more than about 10 g/m², more preferably no more thanabout 8 g/m², and most preferably no more than about 5 g/m².

[0134] Moreover, the combined structure should exhibit a hydrohead valueof at least about 20 mBars, preferably at least about 35 mbars, morepreferably at least about 50 mBars, and most preferably at least about75 mBars.

[0135] In a preferred embodiment, the combined structure of the presentinvention exhibits desired leakage protection or barrier properties atleast equal to that of the absorbent barrier structure.

[0136] Dampness Management Means

[0137] Optionally, as shown in FIG. 1, a dampness management means 26may be included in the absorbent article of the present invention. Thedampness management means 26 may provide further leakage protection.Suitable materials for dampness management means 26 are breathablematerials which permit vapors to escape from the diaper 20. Exemplarymaterials may include apertured films; monolithic or microporous films,preferably with apertures; modified (with respect to pore structures anddistributions) nonwovens or composite materials such as film/nonwovenlaminates.

[0138] Suitable apertured films typically have open surface area atleast about 1%, preferably at least about 5% more preferably at leastabout 10%. In another embodiment, the open surface area may be 0.1% ormore, provided there are sufficient amount of relatively large porespresent. Further, suitable apertured films should have an open surfacearea less than about 20% such that it would have insubstantial effect onthe leakage protection properties of the article. Apertured films may bevacuum formed or hydro-formed to provide macro and/or micro apertures.More detailed descriptions of suitable apertured films can be found inU.S. Pat. No. 4,629,643, U.S. Pat. No. 4,609,518 and U.S. Pat. No.4,695,422, U.S. Pat. No. 4,342,314 and U.S. Pat. No. 4,463,045; thedisclosure of each is incorporated by reference herein.

[0139] In another embodiment, the dampness management means may includezones of different breathability and/or liquid permeability. Forexample, the dampness management means may be higher in breathabilityand/or liquid permeability in zones which do not coincide with theabsorbent core. As used herein, the term “breathability” refers to thediffusive transport of water vapor through the material. The dampnessmanagement means may be assembled of one or more layers and preferablyincludes at least one layer which is liquid impermeable, the liquidimpermeable layer preferably located adjacent the absorbent core andpreferably covers an area at least as large as the absorbent core.

[0140] Further, moisture condensation on the outer surface (i.e., thegarment side) of the absorbent article leads to dampness to the touch,which reduces wearer comfort and is often perceived as a performanceproblem with the article. The convective transport of moisture vaporthrough the absorbent article of the present invention is very effectivesuch that it may lead to moisture condensation on the outer surface ofthe article and the perceived dampness problem. Thus, it may bebeneficial to incorporate a relatively low breathability dampnessmanagement means into the article of the present invention. Suitable lowbreathability dampness management means should have a MVTR of no morethan about 4500 g/m²/24 hrs, preferably of no more than about 3500g/m²/24 hrs, more preferably no more than about 3000 g/m²/24 hrs, andmost preferably no more than about 2500 g/m²/24 hrs.

[0141] The dampness management means may be disposed between the outercover and the absorbent barrier structure of the present invention.Alternatively, the dampness management means may be disposed within theabsorbent barrier structure between the absorbent layer and one or bothof the barrier layers.

[0142] Other Components

[0143] In addition, the diaper, as represented in FIG. 3, may furtherinclude a pair of fasteners 40 which are employed to secure the diaperabout the waist of the wearer. Suitable fasteners include hook-and-looptype fasteners, adhesive tape fasteners, buttons, snaps,mushroom-and-loop fasteners and the like. The diaper of the presentinvention may also include elasticized leg bands which help secure thediaper to the wearer and, thus, help reduce leakage from the diaper.Similarly, it is also known to include a pair of elasticized,longitudinally extending containment flaps which are configured tomaintain a substantially upright, perpendicular arrangement along thecentral portion of the diaper to serve as an additional barrier to thelateral flow of body exudates.

[0144] It is also common to include a surge management layer positionedbetween the topsheet and the absorbent core in order to help preventpooling of fluids on the portion of the diaper adjacent the wearer'sskin.

[0145] The articles of the present invention may also include wastemanagement features, such as pockets for receiving and containing waste,spacers which provide voids for waste, barriers for limiting themovement of waste in the article, compartments or voids which accept andcontain waste materials deposited in the diaper 20, and any combinationsthereof.

[0146] Optionally, the absorbent articles of the present invention mayinclude a skin care composition, preferably on the skin-contactingsurfaces of the article. The skin care composition useful herein isdirected to maintain and/or improve the skin condition of the skin underan absorbent article or skin that is subjected to chronic or acuteexposures to body exudates, moisture, irritants, etc. It is preferredthat the skin care composition provides a protective, and preferablynon-occlusive function (e.g., a relatively liquid impervious but vaporpervious barrier) to avoid skin overhydration and skin exposure tomaterials contained in body exudates (e.g., urine, feces, menstrualfluids). It is also preferable that the skin care composition providesan abrasion minimizing function to reduce skin irritation in the areaswhere the absorbent article is in contact with the wearer's skin.Additionally, the skin care composition may contain skin careingredients, which directly or indirectly, deliver skin care benefits,such as reduction of overhydration, reduction of redness, skinconditioning, and removal or reduction of skin irritants in bodyexudates. It is also preferred that the skin care composition containsemollients that protect or improve the skin against chaffing, roughness,wrinkled appearance or itchiness. The skin care composition may alsocontain skin soothing agents, such as aloe vera, and chamomile.

[0147] Skin care compositions suitable for use in the present inventionare described in U.S. patent application Ser. Nos. 08/926,532 and08/926,533, each filed on Sep. 10, 1997; U.S. patent application Ser.Nos. 09/041,509, 09/041,232 and 09/041,266, each filed on Mar. 12, 1998;U.S. patent application Ser. No. 09/563,638, filed on May 2, 2000; U.S.Pat. No. 5,607,760 issued Mar. 4, 1997; U.S. patent application Ser. No.09/466,343, filed on Dec. 17, 1999; U.S. Pat. No. 5,609,587 issued Mar.11, 1997; U.S. Pat. No. 5,635,191 issued Jun. 3, 1997; U.S. Pat. No.5,643,588 issued Jul. 1, 1997; and U.S. Pat. No. 6,153,209 issued Nov.28, 2000; the disclosures of which are hereby incorporated by reference.

[0148] Making the Absorbent Barrier Structure

[0149] In one embodiment, the nonwoven web and the cellulosic webforming the absorbent barrier structure are adhesively bonded togetherusing Ato-Findley adhesive H2031F. The nonwoven web is unwound from asupply roll and advances to the spray station where the adhesive ispre-heated to its melt state and sprayed (using a DYNATEC® spray head)onto the web substrate before the nonwoven web is assembled with thecellulosic web to form the absorbent barrier structure. The adhesiveforms three continuous stripes along the longitudinal direction of theadvancing web. The stripes are substantially parallel. Each stripe is 22mm in width and the outer stripes are about 4 mm from the peripheries ofthe web.

[0150] In another embodiment, the first nonwoven web and the cellulosicweb may be adhesively joined together according to the method describedabove. A second nonwoven web is unwound from a supply roll, spray-coatedwith adhesives, then joined to the free surface of the cellulosic web.In another three-layered absorbent barrier structure, the two nonwovenwebs may be unwound from separate supply rolls and spray-coated withadhesives, then simultaneously joined to the opposed surfaces of thecellulosic web.

[0151] The absorbent barrier structure may be incorporated into adisposable diaper having the general construction as the diaper shown inFIG. 1 following well-known assembly processes. Typically, the absorbentbarrier structure is disposed between the absorbent core and the outercover. In a two-layered construction, the barrier layer is disposedadjacent to the garment-facing side of the absorbent core and theabsorbent layer is disposed adjacent to the outer cover. In athree-layered construction, the first barrier layer is disposed adjacentto the garment-facing side of the absorbent core and the second barrierlayer is disposed adjacent to the outer cover. Other well knowncomponents may be incorporated within the diaper without departing fromthe spirit of the present invention. Further, the manner and method ofusing these well known components in connection with the absorbentarticle of the present invention will likewise be readily appreciated bythose skilled in the art.

Test Methods

[0152] A. Air Permeability

[0153] The air permeability is determined by measuring the time in whicha standard volume of air is drawn through the test specimen at aconstant pressure. This test is particularly suited to materials havingrelatively high permeability to gases, such as nonwovens, aperturedfilms and the like.

[0154] A TexTest FX3300 instrument (available from Advanced TestingInstruments, Corp., Spartanburg, S.C.) is used. The Test Method conformsto ASTM D737. The test is operated in a laboratory environment typicallyabout 22±2° C. and about 35±15% relative humidity. The test specimen iskept in this laboratory environment for at least 2 hours prior totesting. The test pressure is 125 Pascals and the test area is 38 cm².In this test, the instrument creates a constant differential pressureacross the sample which draws air through the sample. The rate of airflow through the sample is measured in ft³ per min per ft² (ft³/min/ft²)and converted to permeance (in Darcy/mm) according to the Darcy's Law:

K/d(Darcy/mm)=(V*μ)/(t*A*Δp)

[0155] wherein K is the permeability per unit area of the specimen; V/tis the volumetric flow rate in cm³/sec; μ is the viscosity of air(1.86*10⁻⁵ Pa sec); d is the test material thickness in mm; A is thecross sectional area of the specimen in cm²; Δp is the pressuredifferential in Pascal or Pa; and 1 Darcy=9.869*10⁻⁹ cm².

[0156] For each sample, three replicates should be run, and the averagedresult is reported.

[0157] B. Hydrostatic Head (Hydrohead) Pressure Test

[0158] This property determined by this test is a measure of the liquidbarrier property (or liquid impermeability) of a material. Specifically,this test measures the hydrostatic pressure supported by the material atthe point when water penetration through the material first occurs.

[0159] A TexTest Hydrostatic Head Tester FX3000 (available from AdvancedTesting Instruments, Corp., Spartanburg, S.C.) is used. The test methodconforms to Edana 120.1-18. For this test, pressure is applied to adefined sample portion and gradually increases until water penetratesthrough the sample.

[0160] The test is conducted in a laboratory environment typically about(22±2° C.) and a relative humidity of about 35±15%. The test specimen iskept in this laboratory environment for at least 2 hours prior totesting. The sample is clamped over the top of the water reservoir ofthe instrument, using gasketing material to prevent side leakage duringtesting. When testing an absorbent barrier structure of the presentinvention, which comprises a layer of a barrier material and a layer ofa reservoir material, the sample is oriented such that the layer of thebarrier material faces the water during the test. The area of watercontact with the sample is 28 cm².

[0161] The water pressure is increased at a rate of 3 mBar/min. Thus,the sample is subjected to a steadily increasing water pressure on thesurface of the barrier layer. When water breakout appears on threelocations on the top surface of the sample, the pressure at which thethird breakout occurs is recorded. For some samples, the water breakoutsat various locations may occur temperaneously, the pressure at theinstant the breakouts occur is recorded. If water immediately penetratesthe sample (i.e., the sample provided no resistance), a zero reading isrecorded. For each material, three specimens are tested and the resultsare averaged.

[0162] C. Liquid Impact Transmission Test

[0163] The properties determined by this method correlate with the fluidresistance capability under sudden impact, which relates to leakageprotection, provided by the absorbent structure of the presentinvention. In this test, a sample of the absorbent structure is layeredwith a loaded absorbent core simulant, and the combination is subjectedto an impact force. The properties determined by this method is relevantto the actual use condition where the wearer (especially a baby) fallingfrom a standing position, thus, applying an impact force on a loadeddiaper.

[0164] Liquid impact transmission test is measured with the apparatus9100 shown in FIGS. 5A and 5B. The receiving table 9120 is supported byfour adjustable legs, which level the receiving table 9120. The impactassembly includes a head 9107 and an arm 9110. The head 9107 includes ahammer 9108 (a metal cylinder of 63 mm in diameter) mounted on a baseplate 9109. The arm 9110 is attached to the base plate 9109 on one endand is pivotally attached to hinge 9118 on the other end. The lengthfrom hinge 9118 to the distal end of the base plate 9109 is about 551mm. The arm 9110 is attached to a mounting piece 9114 by a release pin9112. The mounting piece 9114 is positioned (by knob 9116) at a desired(typically 30°) angle with respect to the horizontal table 9120.

[0165] An energy absorbing impact pad 9205 is 12.7 cm by 12.7 cm (5inches by 5 inches) and 0.79 cm (0.3125 inches) thick. The energyabsorbing impact pad 9205 is made of silicone rubber sheeting (Part no.8632 K37, available from McMaster Carr of Cleveland, Ohio). The energyabsorbing impact pad 9205 is attached to a metal plate 9206 of the samedimension. The metal plate 9206 is supported by a shock absorber 9207(Model MA 600 from Ace Controls, Inc., Farmington, Mich.). The bottomsurface of the metal plate 9206 is about 10 mm above the receiving table9120 in the starting position (FIG. 5A). The adjustment knob 9208 of theshock absorber 9207 is set (at about 5) to smooth the decelerationthroughout the stroke. When properly set-up, the hammer 9108 renders adead blow (i.e., no observable rebound) on the sample assembly.

[0166] An absorbent core simulant 9204 is placed is centrally placed ontop of the energy absorbing impact pad 9205. The absorbent core simulant9204 comprises four layers of No. 4 filter paper (70 mm diameter)available from Whatman Laboratory Division, Distributed by VWRScientific of Cleveland, Ohio. The core simulant 9204 is evenly loadedwith 2 grams of simulated urine. The simulated urine is an aqueous 0.9%by weight saline solution, exhibiting a surface energy value of 72.5mN/m as conventionally determined.

[0167] Sample 9203 is a barrier absorbent structure of the presentinvention that includes a barrier zone and a reservoir zone arranged inlayers. Sample 9203 is centrally placed over the core simulant 9204,with the barrier layer facing the core simulant 9204. The surface areaof the core simulant 9204 and sample 9203 are slightly larger than thesurface area of block 9108, which is 63 mm in diameter (0.003117 m² inarea).

[0168] An absorbent material 9202 is weighed to the nearest 0.0001 gramand placed on top of sample 9203 to absorb and retain simulated urine,which passes through sample 9203. The absorbent material 9202 comprisesa No. 4 filter paper (70 mm diameter) available from Whatman LaboratoryDivision.

[0169] A weight 9201 is centrally placed on top of absorbent material9202 to weigh down the sample assembly. The weight 9201 is made ofPlexiglas, measures 5″ by 5″ (12.7 cm by 12.7 cm) and weighs about 206gm. The weight 9201 has a circular hole in the center whose diameter (75mm) is slightly larger than the diameter of the hammer 9108. When arm9110 is released, hammer 9108 strikes through the central hole in weight9201 and renders a dead blow on the central portion of the sampleassembly.

[0170] In the pre-test position (FIG. 5A), the arm assembly is held atthe same angle as the mounting piece 9114 by release pin 9112. Toinitiate the impact test, the release pin 9112 is pulled, whereby arm9110 changes from a starting position, as shown in FIG. 5A, to ahorizontal final position, as shown in FIG. 5B. A stop watch isactivated upon impact to time the experiment.

[0171] In the particular set-up described above, hammer 9108 reaches anacceleration of 70 times gravity when the metal plate 9206 touches thereceiving table, thereby initiating the deceleration. Thus, the impactassembly applies an impact force of 2060 Newtons (according to theformula: force=weight*acceleration) on the sample assembly. Anaccelerometer (model 353B02, available from PCB Piezotronics, Inc.Depew, N.Y.) may be used to measure the acceleration. To obtain theweight, the release pin 9112 is pulled to free the impact assembly fromthe mounting piece 9114; then, the receiving table 9120 is tilted to theposition that places arm 9110 in a horizontal position and hammer 9108resting on a top-loading balance. The weight registered on the balanceis used in the formula above. For the particular set up used herein, theweight is about 3 kg. The weight and length of the impact assembly aswell as the angle of the mounting piece 9114 may be different from thosespecified above, so long as these elements together provide an impactforce of 2060 Newtons upon impact.

[0172] The impact assembly is then allowed to rest in this horizontalposition for two minutes. The arm 9110 is raised and the filter paper9202 is removed and placed on a balance. The weight of the filter paper9202 at three-minutes from impact is recorded. The Liquid ImpactTransmission (LIT) value is calculated and expressed in grams/m² usingthe following formula:

LIT=[final weight of the filter paper−initial weight of the filterpaper]/[impact area]

[0173] wherein the impact area, expressed in m², is the area of the coresimulant 9204 (about 0.003848 m²). For each material, three specimensare tested and the averaged result is reported.

[0174] D. Static Liquid Transmission Test

[0175] The property determined by this test correlates with the fluidretaining ability (or leakage protection) provided by the absorbentbarrier structure of the present invention under an impact and sustainedpressure condition. The property determined by this test is relevant tothe actual use condition where the wearer suddenly moves from a standingposition to a second position (e.g., sitting), and maintains the secondposition for an extended time period.

[0176] The equipment and sample set-up are the same as those describedabove in the Liquid Impact Transmission Test, except in this test, arm9110 is dropped to deliver an impact force of 2060 Newtons and isallowed to rest on the sample for a set period of time (the “holdtime”). Arm 9110 is then raised, the filter paper 9202 is removed andweighed, and the change in weight is reported as described above. Thehold times at the horizontal resting position are 2, 5, 8, 15, 30 and 60minutes.

[0177] E. Moisture Vapor Transmission Rate

[0178] The Moisture Vapor Transmission Rate (MVTR) determines the amountof moisture adsorbed by calcium chloride in a “cup” like container thatis covered by a test specimen. The moisture source is a controlledtemperature and humidity environment (40±3° C. and 75±3% relativehumidity) separated from the calcium chloride by the test specimen. Thismethod is applicable to test specimens such as thin films, multi layerlaminates and the like.

[0179] The sample holding cup is a cylinder with an inner diameter of 30mm and an inside height from bottom to top flange of 49 mm. A flangehaving a circular opening to match the opening of the cylinder can befixed by screws, and a silicone rubber sealing ring with an openingmatching the inner diameter of the cup fits between the top flange andthe cylinder. The test specimen is positioned such that it covers thecylinder opening. The specimen is securely fixed between the siliconerubber sealing and the upper flange of the cylinder so it acts as abarrier to moisture transport.

[0180] The equipment as well as the test specimen should be equilibrated(about two hours or more) to the temperature of the controlledenvironment prior to testing.

[0181] The absorbent desiccant material is CaCl₂, such as can bepurchased from Wako Pure Chemical Industries Ltd., Richmond, Va. underthe product designation 030-00525. If kept in a sealed bottle, it may beused directly. It may be sieved to remove lumps or fines, if existing.It may also be dried at 200° C. for about 4 hours prior to use.

[0182] The CaCl₂ is poured into the cup. The cup is tamped down 10times. Then a spacer is used to set a 1 cm gap between the top of theCaCl₂ and the top of the cup.

[0183] A test sample, cut to about 3.2 cm by 6.25 cm, is placed flat andoverlapping the opening of the cup. The silicone rubber seal and theflange are placed on top of the sample and aligned with the screw holesand are affixed by the screws without over tightening. The total weightof the cup assembly is accurately recorded to three decimal places, andthe assembly is placed into the constant temperature/humidity chamber.

[0184] After 5 hours exposure to the test humidity (without opening ofchamber), the sample is removed and immediately covered tightly with anon-vapor permeable plastic film such as SARAN WRAP. After cooling about30 minutes to allow for temperature equilibration, the plastic film isremoved and the assembly is reweighed.

[0185] The MVTR value is then calculated by determining the moistureincrease over 5 hours due to transport through the 3 cm circular openingand converting the result to units of grams per meter square per 24hours (g/m²/24 hr). For each sample, three replicates should be run, theresulting values will be averaged, and the result rounded to the nearest100 value.

[0186] F. Post-Compression Air Permeability

[0187] When a material, especially one with a relatively flexible oropen structure, is subjected to compaction or sustained pressure, thematerial may experience structural changes. After the applied forces areremoved, the material may not return to its original state completely.This residual structure change often results in changes in properties,such as air permeability. This test method is a measure of theresilience of the sample material after it has been subjected tocompaction or a sustained pressure for a predetermined period of time.

[0188] When an absorbent barrier structure of the present invention isincorporated into absorbent articles, such as diapers, the articles areoften packaged in a highly compact condition, and stored under suchcondition for an extended period of time. Moreover, while the absorbentarticle is worn, the wearer may subject the article to sudden impactforce (e.g., the wearer moves from a standing to a sitting positionabruptly), which may be followed by a sustained pressure (e.g., thewearer maintains the sitting position). Certain materials or structuresare susceptible to change under such conditions, and do not recover totheir original state even after the compaction or pressure has beenremoved. Thus, a material or structure may have high air permeabilitywhen made, but may not be able to deliver such performance after it hasbeen compacted and stored in a package or when it suffers sustainedpressure applied by a wearer.

[0189] Samples (typically, multi-layered laminates) are cut to 40 mm by165 mm in size. The samples are stacked and placed between two Plexiglasplates. Weight is applied over the Plexiglas plates, resulting in apressure of 50 g/cm² (0.7 psi), thereby the overall caliper of the stackof sample sheets is reduced. The level of compression is calculatedaccording to the following:

H=k×n×d

[0190] wherein

[0191] H is the overall caliper after pressure is applied to compressthe sample stack;

[0192] d is the initial caliper of a sample sheet;

[0193] n is the number of sample sheets; and

[0194] k is the compression level.

[0195] The compressed sample stacks are placed inside aclimate-controlled chamber at 60° C., 50% relative humidity, for apre-determined time period. Typically, the test is done with fivesamples in each stack and at 50% compression.

[0196] Air permeability of the sample is determined before compressionand after 24 hours in compression. The post compression air permeabilityis measured after a waiting period, which is sufficient to allow thesample to recover (taking into consideration that the sample may exhibitpermanent deformation and will not recover to its original,pre-compression state). For this test, the air permeability isdetermined by measuring the time in which a standard volume of air isdrawn through the test specimen at a constant pressure and temperature.

[0197] The samples (e.g., the absorbent barrier structure prepared withpre- or post-compression sheets) are conditioned in a temperature andhumidity controlled environment, at 22±2° C. and 35±15% relativehumidity for at least 2 hours before testing.

[0198] The test equipment as manufactured by Hoppe & Schneider GmbH,Heidelberg, Germany, under the designation “Textiluhr nach Kretschmar”,is essentially a bellows in a vertical arrangement, with its upper endbeing mounted in a fixed position, and the lower end being releasablyhold at its upper position, which can be loosened by means of a releasehandle to slide under controlled conditions to the lower position,thereby increasing the volume inside the bellows by pulling air throughthe test specimen which is covering the air entering opening at theupper end of the bellows. The test specimen is firmly hold to cover theair entering opening by means of a fastening ring of 5 cm² or 10 cm² toallow for different samples sizes and/or different permeability ranges.If the 10 cm² ring is used, the sample should be at least 55 mm wide,for the 5 cm² ring at least 35 mm. For both, the samples should have alength of about 150 mm.

[0199] In case of very high permeability materials, the opening can befurther reduced, with appropriate adjustments to the equipment andcalculation.

[0200] The equipment comprises a stopwatch ({fraction (1/100 )} sec)which automatically measures the time between the operation of therelease handle which starts the sliding of the bellows, and the stop ofthe bellows when their bottoms reach the lower end.

[0201] The air permeability k of the material is calculated by the Darcylaw as described above, wherein different parameters are used (due tothe differences in equipment set-up). Specifically for the testequipment used here, V is 1900 cm³, A is 4.155 cm² and Ap is 160 Pa.

[0202] The test is repeated once for each test sample (either sheetsmade of single material or laminates of different materials), and shouldbe repeated on five samples. For each sample material or laminate, theaverage of at least three satisfactory runs is reported. The averagedvalue is reported in Darcy/mm, taking into account the unit thickness ofthe material.

[0203] G. Absorption Test

[0204] This test measures the high suction capillary absorption ofabsorbent materials. Capillary sorption is a fundamental property of anyabsorbent that governs how fluid would be absorbed by the absorbentstructure. High suction capillary sorption characterizes the ability ofa material to partition fluid from competing materials.

[0205] A porous glass frit is connected via an uninterrupted column offluid to a fluid reservoir whose fluid level is located at the sameheight as the horizontal center of the frit porous structure. The sampleabsorbs fluid upon demand and its weight at equilibrium is recorded. Thefixed height capsorption experiment thus gives information about theliquid uptake (g/g) in the horizontal direction.

[0206] Experimental Setup

[0207] The test liquid used herein is 0.2 wt % TRITON® X-100 (availablefrom Sigma-Aldrich Inc.) aqueous solution having a surface tension ofabout 33 dyne/cm). This test method may be adapted to use other testliquids such as water or synthetic urine (having a surface tension ofabout 75 dyne/cm and about 55 dyne/cm, respectively).

[0208] A porous glass fritted funnel is filled with the test liquid. Thefritted funnel (available from VWR Scientific Products, Cleveland, Ohio)has a 350 ml volume and 10-15 micron pores; its bottom outlet ismodified by glass blower to accommodate tubing. The fritted funnel isinverted such that the funnel opening is resting on a flat surface andthe bottom outlet is facing up. A 1.40 m long piece of Tygon tubing(Part No. R3603, available from VWR Scientific Products) is attached tothe funnel bottom and filled with test liquid. The fritted funnel isthen turned upright and clamped onto a stand. The Tygon tubing end issecured to the fritted funnel with the tubing end raised severalcentimeters above the fritted disk.

[0209] The funnel is filled with 100 ml of test liquid (the raisedtubing end prevents the liquid from draining through the frit) andcovered with plastic wrap. The frit is then stored for 5-12 hours toallow any air trapped in the frit pores to escape. Any observable airbubbles should also be removed from the frit or the tubing. For testing,the Tygon tubing is placed in the glass fluid reservoir (20-25 cmdiameter) filled with test liquid. The center of the frit and the fluidlevel in the reservoir are set to the same height. A level is used toensure that the frit surface is horizontal.

[0210] In between experiments the fritted funnel is covered with plasticwrap to prevent evaporation and drying of the test liquid in the fritpores; however, during an experiment the fritted funnel is not covered.

[0211] If frits are not used for several hours, they should be stored asfollows: the Tygon tubing is removed from the fluid reservoir andsecured to the fritted funnel with the tubing end raised severalcentimeters above the fritted disk. The funnel is filled with 100 ml oftest liquid (the raised tubing end prevents the liquid from drainingthrough the frit) and covered with plastic wrap.

[0212] Experimental Procedure

[0213] Ensure that no observable air bubbles are trapped below the fritor in the tubing. Cut a 5.40 cm diameter sample using an arch punch.Weigh the sample. Clamp off tubing below fritted funnel. Place the pupcylinder onto the frit surface centered. Place the sample into the pupcylinder, making sure that it is centered and lying flat on the fritsurface. Gently insert the pup piston into the pup cylinder over thesample. Place a ring weight on the pup cylinder. Remove the clamp andallow the samples to absorb for 2.5 minutes. Remove the ring weight, thepup piston, the pup cylinder and then the sample from frit. If it isnecessary to lower the fritted funnel or tilt it for sample removal, thefritted funnel tubing has to be clamped off below the fritted funnelprior to removing the sample from the frit (to ensure that no additionalfluid is absorbed by the sample during removal). Weigh the sample.Repeat procedure with the next sample. Perform two_replicates for eachsample and report the net uptake obtained for each sample as well as theaverage net uptake. Report which frits were used (frit number or otheridentification). If results of the two tests differ by more than 10%(based on the higher value), check frits and sample preparation andrepeat the experiment. The liquid absorption (or uptake) by the sampleis calculated according to the following:

Net uptake,g/g=(sample wet weight,g−sample dry weight, g)/sample dryweight,g

EXAMPLES Example 1

[0214] In this example, the absorbent barrier structure of the presentinvention is a two-layered laminate comprising an absorbent zone and abarrier zone substantially superimposed over the barrier zone. FIG. 2Aillustrates this embodiment schematically, wherein the absorbent barrierstructure 10 includes a barrier layer 12 and an absorbent layer 14. Theabsorbent layer is a natural fiber cellulosic web commercially availableas BOUNTY® paper towel (manufactured by the Procter and Gamble Company,Cincinnati, Ohio). BOUNTY® has a two-ply construction, with a totalbasis weight of about 43 gsm and a total thickness of about 0.686 mm.The barrier layer is a polypropylene spunbond/meltblown nonwoven web(manufactured by BBA Nonwovens, Simpsonville, S.C. under the designationMD2005) which has a basis weight of about 27 gsm and a thickness ofabout 0.305 mm.

Example 2

[0215] In this example, the absorbent barrier structure has athree-layered structure, which includes a first and a second barrierzones are disposed on the opposed sides of the absorbent zone. FIG. 2Billustrates this embodiment schematically, wherein the absorbent barrierstructure 10 includes two barrier layers 12 and 16 and an absorbentlayer 14 between the two barrier layers. The absorbent layer is atwo-ply BOUNTY® paper towel. The first and the second barrier layers aremeltblown polypropylene nonwoven webs (manufactured by JentexCorporation, Buford, Ga. with the designation PP-015-F-N, X2009A). Eachof the MB nonwoven web has a basis weight of about 15 gsm.

Example 3

[0216] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 2, exceptthat the first barrier layer is a MB polypropylene nonwoven web fromJentex (PP-010-F-N, X2009A) with a basis weight of about 10 gsm. Thesecond barrier layer is a spunbond/spunbond polypropylene nonwoven webmade of microdenier fibers with a basis weight of about 17 gsm(available from First Quality Fibers Nonwovens, Hazelton, Pa. under thedesignation GCAS 16002184).

Example 4

[0217] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 2, exceptthat the first barrier layer is a MB nonwoven web from Jentex(PP-005-F-N, X2009A) with a basis weight of about 5 gsm and the secondbarrier layer is a MB nonwoven web from Jentex (PP-010-F-N, X2009A) witha basis weight of about 10 gsm.

Example 5

[0218] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 2, exceptthat the first barrier layer is a MB nonwoven web from Jentex(PP-010-F-N, X2009A) with a basis weight of about 10 gsm and the secondbarrier layer is a MB nonwoven web from Jentex (PP-005-F-N, X2009A) witha basis weight of about 5 gsm.

Example 6

[0219] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 2, exceptthat the absorbent layer is a single-ply BOUNTY® paper towel.

Example 7

[0220] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 3, exceptthat the absorbent layer is a single-ply BOUNTY® paper towel.

Example 8

[0221] In this example, the absorbent barrier structure hassubstantially the same construction as described in Example 2, exceptthat the absorbent layer comprises two superimposed layers of single-plyBOUNTY® paper towel.

[0222] The properties of the above examples are tested according to theTest Methods disclosed herein. For the three-layered structure, thefirst barrier layer is disposed adjacent to the absorbent core duringthe tests. The test results are summarized in Table 1 below. The testresults in Table 1 indicate that the present invention provides a uniquestructure having the desirable balance of properties. TABLE 1 LIQUIDIMPACT AIR TRANS- PERME- HYDROHEAD MISSION BASIS ABILITY PRESSURE VALUEWEIGHT EXAMPLE (Darcy/mm) (mBars) (gsm) (gsm) 1 57 41.3 7.2 70 2 24 49.36.8 73 3 51 45.3 8.3 69.3 4 47 23.5 7.4 57.1 5 46 39.3 8.5 57.1 6 2455.5 10.5  54 7 59 33.7 13.2  51 8 21.4 81.5 7.1 78

COMPARATIVE EXAMPLES

[0223] Comparative Example 1 is a two-ply BOUNTY® paper towel.

[0224] Comparative example 2 is a formed film having angled capillarieson its surface such as those described in EP 934,735 and EP 934,736. Theformed film is made of polyethylene and is available from Tredegar FilmProducts Corporation, Terre Haute, Ind.

[0225] Comparative example 3 is a microporous film. The microporous filmis made of polyethylene having 40-45 wt % CaCO3 fillers. The microporousfilm is available from Clopay Plastic Products Company, Cincinnati,Ohio.

[0226] Comparative example 4 is a polypropylene SS nonwoven webavailable from First Quality Fibers Nonwovens, Hazelton, Pa. under thedesignation GCAS 16002184.

[0227] Comparative Example 5 is a polypropylene MB nonwoven webavailable from Jentex Corporation, Buford, Ga.) with the designationPP-015-F-N, X2009A.

[0228] The properties of the comparative examples are tested accordingto the Test Methods disclosed herein. For the three-layered structure,the first barrier layer is disposed adjacent to the absorbent coreduring the tests. The test results are summarized in Table 2 below.TABLE 2 LIQUID IMPACT AIR TRANS- COMPAR- PERME- HYDROHEAD MISSION BASISATIVE ABILITY PRESSURE VALUE WEIGHT EXAMPLE (Darcy/mm) (mBars) (gsm)(gsm) 1 143 <0.5 57 43 2 133 3 5 42 3 0.05 >100 0.2 52 4 407 10.8 37 175 53 68.5 25 15

[0229] The test results in Table 2 indicate that the comparativeexamples fail to provide the desirable balance of properties. BOUNTY®paper towel (Comparative example 1) has excellent air permeability butpoor liquid impermeability. Microporous film (Comparative example 2) hasexcellent liquid impermeability but is substantially air impermeable.The nonwoven webs (Comparative examples 3-5) are air permeable andliquid impermeable under general conditions. However, the nonwoven websbecome liquid permeable under impact and/or pressure conditions.

Example 9

[0230] In this example, the absorbent barrier structure has athree-layered construction as described in Example 2 is combined with anouter cover material, which is a polypropylene SM nonwoven web having a16 gsm SB layer and a 11.5 gsm MB layer. The combination structure istested according to the Test Methods described herein. The test resultsare summarized in Table 3. TABLE 3 AIR HYDROHEAD LIQUID IMPACTPERMEABILITY PRESSURE TRANSMISSION EXAMPLE (Darcy/mm) (mBars) VALUE(gsm) 9 13 71.7 5.1 2 24 49.3 6.8

[0231] When compared to the absorbent barrier structure of Example 2,the combined structure enhances the liquid impermeability and resistanceto wet-through under impact but decreases the air permeability. Overall,the combined structure also provides the desired balance of properties.

Example 10

[0232] In this example, the absorbent barrier structure of Example 2 iscombined with an outer cover material according to Example 9. Further,an apertured film is disposed between the second barrier layer ofExample 2 and the outer cover of Example 9. The apertured film is madeof polyethylene having 11.7% open area. The apertures arehexagonal-shaped openings. The apertured film used herein ismanufactured by BP Chemicals, Wassergurg, Germany under the tradedesignation (HEX-B Type 45109). Apertured films manufactured by TredegarFilm Products Corporation, Terre Haute, Ind., under the designationHEX-B, are equally suitable for use herein.

[0233] The overall structure, including the absorbent barrier structure,the apertured film and the outer cover, are tested according to the TestMethods described herein, and are compare with Example 9, which does notinclude the apertured film. The results are summarized in Table 4 below.TABLE 4 LIQUID IMPACT AIR TRANS- PERME- HYDROHEAD MISSION MVTR ABILITYPRESSURE VALUE (g/m²/ EXAMPLE (Darcy/mm) (mBars) (gsm) 24 hrs)  9 1371.7 5.1 3972 10 13 66.2 2.5 3434 (±10)

[0234] The open structure of the apertured film has insubstantial effecton the convective air permeability overall. The apertured film reducesthe liquid impermeability of the overall structure, especially underimpact condition. The results show that the overall structure includingthe addition of the apertured film, still achieves the desired balanceof properties. More importantly, the apertured film reduces thediffusive MVTR of the overall structure. Thus, the unique combination ofpermeabilities provides a structure that desirably exhibits reduceddampness or condensation on the outer surface of the structure.

Example 11

[0235] In this example, the absorbent layer is a cellulosic web (namely,a two-ply BOUNTY® towel) which has been surface-treated with ahydrophobic agent on both sides. The surface treatment method isdescribed in PCT publication WO 00/14296 (D'Agostino et al.), thedisclosure of which is incorporated herein by reference. The hydrophobicagent used is a fluorocarbon, namely, perfluoromethylcyclohexane. Thetreated cellulosic web is disposed between two barrier layers to form athree-layered absorbent barrier structure. Example 11 has substantiallythe same structure as Example 2 except that the treated BOUNTY® is usedin place of the untreated BOUNTY® as the absorbent layer. Table 5 belowshows the properties of this example in comparison to the example usingthe untreated web. TABLE 5 AIR HYDROHEAD LIQUID IMPACT PERMEABILITYPRESSURE TRANSMISSION EXAMPLE (Darcy/mm) (mBars) VALUE (gsm) 11 27 74.34.7  2 24 49.3 6.8

[0236] The results show that the hydrophobic treatment significantlyenhances the liquid impermeability while maintaining the airpermeability.

Example 12

[0237] In this example, example 12 and Comparative example 2 are testedaccording to Test Method G (Post-Compaction Air Permeability). Example12 has substantially the same construction as example 3, except thatboth the first and the second barrier layers are spunbond/spunbondpolypropylene nonwoven webs made of microdenier fibers with a basisweight of about 17 gsm (available from First Quality Fibers Nonwovens,Hazelton, Pa. under the designation GCAS 16002184). The results aresummarized below in Table 6. TABLE 6 PRE-COMPACTION POST-COMPACTION AIRPERMEABILITY AIR PERMEABILITY EXAMPLE (Darcy/mm) (Darcy/mm) Comp. 2 109± 10 66 ± 16 12 115 ± 7  94 ± 8 

[0238] As the test results show that compaction results in insubstantialchange in air permeability of example 12 of the absorbent barrierstructure of the present invention. In contrast, a material, such asComparative example 2, suffers significant loss in air permeability,which is attributable to its structural changes under compaction and itsinability to recover its original structure.

[0239] While particular embodiments of the present invention have beenillustrated and described, it would be apparent to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent article comprising an absorbent coreand an absorbent barrier structure, wherein the absorbent barrierstructure has a hydrohead value of at least about 10 mBars; a convectiveair permeability of at least about 10 Darcy/mm; and a liquid impacttransmission value of less than about 20 g/m².
 2. The absorbent articleof claim 1 wherein the absorbent barrier structure has an absorbency ofat least about 1 g/g.
 3. The absorbent article of claim 1 wherein theabsorbent barrier structure has a static liquid transmission value ofless than about 6.5 g/m² at 2 minutes after impact and less than 13 g/m²at 15 minutes after impact.
 4. The absorbent article of claim 1 whereinthe absorbent barrier structure comprises a reservoir zone, and abarrier zone at least partially disposed between the absorbent core andthe reservoir zone.
 5. The absorbent article of claim 4 wherein theabsorbent barrier structure has a basis weight of at least about 30 g/m²and a thickness less than about 1.5 mm.
 6. The absorbent structure ofclaim 4 wherein the reservoir zone has an absorbency at least about 20%less than that of the absorbent core and the hydrohead value of thebarrier zone is higher than the hydrohead value of the reservoir zoneand the hydrohead value of the absorbent core.
 7. The absorbent articleof claim 6 wherein the reservoir zone comprises a porous structureselected from the group consisting of a fibrous web, a fibrous wad, afoam, and combinations thereof.
 8. The absorbent article of claim 6wherein the reservoir zone has a basis weight of at least about 15 gsm.9. The absorbent article of claim 6 wherein the reservoir zone comprisesat least about 70 wt % of cellulosic fibers.
 10. The absorbent articleof claim 9 wherein the reservoir zone further comprises additivesselected from the group consisting of synthetic fibers, chemical bondingagents, crosslinking agents, debonding agents, wet strength resins,liquid or moisture absorbing agents, odor absorbing agents,antimicrobials, coloring agents, stiffening agents and mixtures thereof.11. The absorbent article of claim 4 wherein the hydrohead value of thebarrier zone is at least about 10 mBars.
 12. The absorbent article ofclaim 4 wherein the barrier zone is made from polymeric materialsselected from the group consisting of polyolefins, olefinic copolymers,polyesters, polyamides, polyalkylene oxides, polyvinyl alcohols, andmixtures thereof.
 13. The absorbent article of claim 4 wherein thebarrier zone includes a fibrous web selected from the groups consistingof a woven web, a knitted web, a spunbond nonwoven web, a meltblownnonwoven web, a spunbond/meltblown nonwoven web, aspunbond/meltblown/spunbond nonwoven web, a carded nonwoven web, anair-laid nonwoven web, a hydro-entangled nonwoven web, and combinationsthereof.
 14. The absorbent article of claim 4 wherein at least onesurface of the reservoir zone or the barrier zone is treated with ahydrophobic agent.
 15. The absorbent article of claim 14 wherein thehydrophobic agent is a fluorocarbon.
 16. The absorbent article of claim4 further comprises a topsheet and an outer cover, wherein the absorbentcore is disposed between the topsheet and the outer cover; and theabsorbent barrier structure is disposed between the absorbent core andthe outer cover; wherein a combination of the absorbent barrierstructure and the outer cover has a hydrohead value of at least about 25mBars; a convective air permeability of at least about 10 Darcy/mm; anda liquid impact transmission value of less than about 20 g/m².
 17. Theabsorbent article of claim 16 wherein the combination of the absorbentbarrier structure and the outer cover has a MVTR of no more than 3500g/m²/24 hrs.
 18. The absorbent article of claim 16 wherein the outercover is a nonwoven web, an apertured film or a laminate thereof. 19.The absorbent article of claim 16 wherein the absorbent barrierstructure comprises a first barrier zone disposed adjacent to agarment-facing surface of the absorbent core and a reservoir zonedisposed between the barrier zone and the outer cover.
 20. The absorbentarticle of claim 19 wherein the absorbent barrier structure furthercomprises a second barrier zone disposed at least partially between thereservoir zone and the outer cover.
 21. The absorbent structure of claim20 further comprises a dampness management means disposed between theabsorbent barrier structure and the outer cover, or between thereservoir zone and one of the barrier zones.
 22. The absorbent structureof claim 21 wherein the absorbent barrier structure, the dampnessmanagement means and the outer cover together has a MVTR of no more than4500 g/m²/24 hrs.
 23. The absorbent structure of claim 21 wherein thedampness management means is an apertured film having no more than about20% open surface area.
 24. An absorbent article comprising an absorbentcore and a barrier structure, wherein the barrier structure has aconvective air permeability of greater than about 10 Darcy/mm; a liquidimpact transmission value of less than about 20 g/m²; and apost-compression air permeability decrease of no more than about 35%.25. The absorbent article of claim 24 wherein the barrier structure hasa hydrohead value of at least about 10 mBars.
 26. The absorbent articleof claim 24 wherein the barrier structure comprises a reservoir zone anda barrier zone at least partially disposed adjacent to the absorbentcore.
 27. The absorbent article of claim 26 wherein the reservoir zonehas an absorbency at least about 20% less than that of the absorbentcore and the barrier zone has a hydrohead value that is higher than thatof the reservoir zone and that of the absorbent core.
 28. The absorbentarticle of claim 26 wherein the absorbent barrier structure has a basisweight of at least about 30 g/m² and a thickness less than about 1.5 mm.29. The absorbent article of claim 26 further comprises a topsheet andan outer cover, wherein the absorbent core is disposed between thetopsheet and the outer cover; and the barrier structure is disposedbetween the absorbent core and the outer cover; wherein a combination ofthe barrier structure and the outer cover has a hydrohead value of atleast about 10 mBars; a convective air permeability of at least about 10Darcy/mm; and a liquid impact transmission value of less than about 20g/m².
 30. The absorbent article of claim 29 wherein the reservoir zoneis a cellulosic web, the barrier zone is a nonwoven web, and the outercover is a nonwoven web or an apertured film.
 31. The absorbent articleof claim 30 wherein the barrier structure comprises a first fibrousbarrier zone disposed adjacent to a garment-facing surface of theabsorbent core and a reservoir zone disposed between the fibrous barrierzone and the outer cover.
 32. The absorbent article of claim 31 whereinthe barrier structure further comprises a second fibrous barrier zonedisposed between the reservoir zone and the outer cover.
 33. Theabsorbent article of claim 32 further comprising a dampness managementmeans disposed between the barrier structure and the outer cover orbetween the reservoir zone and one of the barrier zones.
 34. Theabsorbent article of claim 33 wherein the dampness management means isan apertured film having less than about 20% open surface area.